THE LAW OF INHERITANCE; 
OR, 
THE PHILOSOPHY OF BREEDING. 
“ Still, through her motes and masses draw 
Electric thrills and ties of law, 
3 
Which bind the nature.!’ 
— Emerson. 
By E . L E W IS STUB T E V A N T, M . D ., 
Wausiiakum Farm, South Framinoham, Mass. 
[From tlu122<l Annual Report of the Secretary of the Massachusetts State Board of Agriculture.! 
BOSTON: 
W RIGHT & POTTER, STATE P R I N T E R S, 
79 Milk Street (corner of Federal). 
1875. THE LAW OF INHERITANCE; 
OR, 
THE PHILOSOPHY OF BKEEDING. 
“ Still, through her motes and masses draw 
Electric thrills and ties of law, 
Which bind the strength of nature.” 
— Emerson. 
By E . LEWIS S T U II T E V A N T, M . D ., 
Wausiiakum Farm, South Framingham, Mass. 
[From the 22d Annual Report of the Secretary of the Massachusetts State Board of Agriculture.] 
BOSTON : 
WRIGHT & POTTER, STATE PRINTERS, 
79 Milk Street (corner of Federal). 
1875. THE LAW OF INHERITANCE; 
OK, 
THE PHILOSOPHY OF BREEDING. 
It is now nearly three years since I made my first attempt to 
write a work on the breeding of domestic animals. I had 
collected a considerable mass of information, chiefly so-called 
facts, and it seemed an easy matter to bring these into shape 
for the illustration of principles which could be enunciated as 
laws. I soon, however, realized the difficulty of using this 
material to produce an harmonious result, as the grouping was 
not only arbitrary, but the laws which they were intended to 
illustrate were but empirical formulae, whose mutual connec- 
tions could not be shown. I therefore determined to seek, 
through further study, a solution for my difficulties ; and I 
may here say that my realization of the importance of force 
as fashioning the phenomena of vitality came entirely from a 
series of inductions. The facts were grouped under laws 
which seemed to formulate the conditions under which they 
occurred, and these laws, in turn considered as unities, pointed 
unmistakably to a superior law, which in its turn influenced 
their occurrence,—the law of persistence of force. This 
brief paper is not presented in order to prove a theory, 
but as an outgrowth arising from the supposed recognition 
of a cause. 
The cell was taken as the groundwork of my scheme, for 
microscopic study had familiarized me with these unities of 
vitalized structure, and belief in a reign of law had led me to 2 
The Law of Inheritance ; or, 
a firm conviction that the working of natural law was univer- 
sal ; and if completed structure was governed by any power, 
then the individual parts of that structure must be influenced 
by the same ruling. Hence the search after truth must be 
from the simple to the complex, rather than the reverse. 
Every change of matter must be produced or caused by 
some previous condition, for every effect must have its cause. 
This which accomplishes is called a force, and the change 
is the measure and exponent of the force used. Force is, 
therefore,, a conception of a real existence, which, although 
unseen to our eyes, and not cognizable to our senses, can be 
studied from its effects, for these are seen and recognized, 
and may be grouped; they can in turn be converted into 
the unseen, and again be reconverted into the seen, and, 
through modern science, so measured and accounted for, 
that it may be said with certainty, forces are indestructible. 
Forces are also strictly subject to the law of quantity. 
A given quantity of one force can produce a definite 
quantity of another. The conversion of a force may change 
its apparent character, and the phenomena produced by 
the two forms may be widely different. This is illustrated 
in heat and motion, electricity and magnetism, animal and 
vegetable life. 
Like causes produce like effects when acting in a similar 
manner on similar material. We know that forces may be 
represented by forms, and that difference of form will indi- 
cate a difference in the construction of the force. 
Force is the agent which produces changes. It has, as a 
conception, a numerical value and a direction of action. It 
can, therefore, be increased or diminished, and its direction 
may be interfered with or antagonized by other force. The 
concrete force is the equilibrium of all these opposing forces. 
Any change must be produced by an equivalent change in the 
force which is represented by the object undergoing change. 
This work is but applying the doctrine of persistence of 
force to vitality, as it has already been applied to physics. 
The forces governing vitality, chemistry and physics, must 
needs be but forms of the same force. Nature seems to work 
s 
always under law, and her phenomena, in successive group- The Philosophy of Breeding. 
3 
ings, continually point to governing laws, and these in turn 
to others, until we must conceive of one great final law, in 
infinity, to which all others are subordinate. 
INTRODUCTORY. 
/ 
In the higher classes of animals our first knowledge of the 
individual life is of the union of two germs,—the one fur- 
nished by the female, the other by the male. The product of 
this union is a determinate one, and is influenced in a varied 
degree by multitudinous causes, the more proximate of which 
are parentage and environment, and the more remote the 
antecedents of the individual and the race. 
The, creation of the individual and the fixing of a type for 
a domestic breed is, under law, largely within the power of 
man, and the understanding of the action and reaction of law 
on law, in the production of certain ends of animal structure 
and function, constitutes the science of breeding. 
The science of breeding is not necessarily an exact science. 
It deals Avith concrete phenomena, and its predictions must 
be, in the main, general. By acting in conformity with its 
predictions, the probabilities of the successful attainment of 
our ends in the individual is very largely increased ; when 
individual knowledge of the laws of causation is understand- 
ingly applied to the problem of breeding certain results from 
an animal of known antecedents, the probabilities of the posi- 
tion have a near approach to certainties. 
The scientific breeder is one who applies the laws governing 
the art with an understanding of the reasons upon which his 
expectations are based ; while the practical breeder is one who 
follows rules established by experiment and belief for the 
government of produce and production. It is as the art of 
breeding is united with the science that the best results may 
be expected ; and practice is dependent on science for its 
correctness and the enlargement of its usefulness. 
To the believer in causation—a principle which underlies 
the practise of all science—the animal structure and func- 
tion is a result produced by, and in conformity to, law; and 
were the whole history of all the forces which have taken part 
in the production of individual animals so laid out before a 4 
The Taw of Inheritance ; or, 
mind capable of investigating the process, and which could so 
estimate their various values as to project them in a mechani- 
cal form, a figure could be drawn in which the resultants of 
the forces could be represented by a line, which would inva- 
riably indicate the value of the concrete forces which would 
be the contribution of the parties to reproduction. This is 
to say that certainty of result would follow complete and 
exact knowledge, and the corollary is equally obvious, that 
when we have uncertainty in practice, it can be explained by 
the deficiency of our knowledge. 
To demand this complete knowledge is to demand a mind 
which is infinite to our present conceptions; but it is in our 
power to continuously encroach upon the borders of our igno- 
rance, and, while extending the boundaries of our knowledge, 
gain increased control over the forces of nature. 
The study of physics, or philosophy applied to nature, to 
me, at least, indicates the possibility of " spontaneous * gen- 
eration.” But as this doctrine, so reasonable in itself, is the 
subject of so much prejudice, and not as yet satisfactorily 
demonstrated, we may at present claim that life is always 
derived from preexisting life. The terms which we apply to 
this derivative process are reproduction and generation. The 
word reproduction is general in its meaning, and includes the 
history of the changes which take place in the organs and 
functions of the individual, by means of which new matter is 
formed, as well as the production, growth and development 
of the new germs which make their appearance through gen- 
eration. The word generation, strictly speaking, has refer- 
ence only to the changes immediately following the act of 
begetting, but usually includes somewhat of the past history 
of the separate cells which take part in this process, as well 
as some history of the development of the new life thus 
formed. The generative process appears to consist essen- 
tially in the union of the contents of two cells, or the differ- 
entiated product of one cell, by which the germ of what may 
* Spontaneous: I use the word in the sense of produced without any special cause 
or method being assigned, as of the appearances of life without any evidence of its 
being produced from an existing vitality,—that' is, the convertibility of forces. To 
use the word as if it involved the production of life without cause, or not in accord- 
ance with law, would involve an absurdity of thought. The Philosophy of Breeding. 
5 
become an independent life is the result. Development is the 
sequel to generation. 
The reproductive process in itself consists in the formation 
of certain cells from preceding cells through well-defined 
procedure. It may be by subdivision, by gemmation, or 
through the intervening act of generation. When, by sub- 
division or by gemination, each act of development appears 
to diminish the germinal capacity ; when, by generation, the 
germinal capacity appears to be renewed. By subdivision is 
meant the method of multiplication of cells, which, for a time, 
may retain their juxtaposition ; by gemmation, the forma- 
tion of cells which are to be cast forth, the commencement of 
a separate existence. The reproductive process includes the 
repair of injuries and the increase and renewal of parts. 
Growth may be the sequel to reproduction. 
Life may be said to commence with the cell, for it is only 
at this stage that we ordinarily recognize individuality. In 
the higher animal structures, as in the mammalia, we have 
the whole structure either built of or derived from cells, pre- 
senting a most varied and complex appearance as viewed in 
their completed state, but which, when studied with reference 
to their history and development, are seen to be all derived 
from this same formative element. Each cell is or has been 
at some time, within certain limits, an individual and inde- 
pendent whole, in which the vital processes are or have been 
repeated; as in one, so in all. Although presenting this 
apparent individuality, yet, in the animal structure, these 
separate units are all combined, each with all, to form the 
harmonious whole,—the animal life. 
The study of the cell is the foundation from which the 
science of breeding is to be built up, for natural law is univer- 
sal and simple and unvarying, acting on all alike, but its 
actions disguised by environment. That the law may be seen 
in its primal force, it is necessary that its workings should be 
sought for amid the simplest conditions and amongst the least 
complexity of structure. 
THE CELL. 
The cell proper, or the ideal cell, is a homogeneous and 
extremely simple structure, which may be defined as merely 6 
The Law of Inheritance ; or, 
substance within an enveloping membrane. Within a cell we 
usually expect to find a nucleus, or, possibly, within the 
nucleus another cell, which we call a nucleolus. These inner 
cells are almost invariably of a round or oval form, offer greater 
resistance to the action of chemical agents than do the exter- 
nal parts, and are those parts which are the most constantly 
found unchanged. The nucleus seems less connected with 
the function and specific office of the cell, according to 
Virchow, than with its maintenance and multiplication as a 
living part. 
For the existence of the cellular element, such as we are to 
consider, two things are requisite,—the membrane and the 
nucleus. The contents change according to position and 
function. With these two forms,—the membrane and the 
nucleus,—we are enabled to examine critically the basis of 
some of the phenomena attending life. 
In the embryonic state we can readily detect the time when 
the whole structure is composed of cells, and as we pass 
onward towards birth, we see these cells changing their form 
and function, becoming differentiated as it were, in an increas- 
ing ratio with the age. The cells multiply, change their form 
and their function, which necessarily involves their contents, 
until in the grown individual it is difficult to trace the connec- 
tion between these elements in the various parts. The cells 
change, but while the activity of the cell remains, the nucleus 
can usually be detected. The muscle-cells become elongated 
and become filled with contractile matter, and capable of 
transmitting force ; the nucleus remains attached somewhere 
to this cell and is unchanged. So with the nerve-cells ; the 
contents differ from the muscle-cells, and it is but the nucleus 
which remains to indicate the kinship. We also find changes 
going on in the shapes of cells by outgrowths, by division, by 
absorption, and even by secretion and growth. These cells 
containing nuclei are, in fact, individual units of a living 
organism, and themselves containing life and undergoing vital 
processes, go to make up the concrete life we recognize in the 
formed animal. 
As the processes which these vital unities pass through are 
all allied, we can consider some of the laws of reproduction, as 
derived from the study of the simple or ideal cell, leaving our The Philosophy of Breeding. 
7 
considerations concerning generation until we shall trace the 
union of the sperm and germ cells, and are prepared to study 
the development resulting therefrom. We can the better 
proceed in this course, if it is continually borne in mind that 
the cell is in a certain sense an independent being, and rules 
arbitrarily over certain surrounding limits. In some tissues, 
where there are intercellular substances, each cell rules, as 
pathological investigation shows, over its own defined terri- 
tory. In other tissues in which the cells are contiguous, each 
cell can run its own course without the fate of the cell lying 
next to it being necessarily linked with its own. In a third 
tissue we find the cell-elements more intimately connected 
with each other: as, for instance, a stellate-cell may anasto- 
mose with a similar one, and in this way a reticular arrange- 
ment may be produced similar to that seen in capillary-vessels 
and other analogous structures. Yet even in this chain-work 
of cells, individual cells, in consequence of certain internal 
or external influences, undergo certain changes confined to 
their own limits, and not necessarily participated in by cells 
adjoining. ( Virchow.) 
Each cell in its development reproduces itself.—The manner 
of the development need not concern us in this place. 
Although primarily the ideal cells are in form alike, yet 
through the differentiation arising from complexity of struc- 
ture, we see existing cells of apparently widely different 
origin. We have, for instance, the hepatic-cell, columnar 
epithelium, cells of connective tissue, muscle-cells, nerve- 
cells, etc., etc. In the animal organism there is a continual 
using up of tissues. The food passing into the body supplies 
the material for supplying the wastes, and cells absorbing 
their share at the necessary time reproduce or repair their 
form or their substance. That form of epidermic cells found 
in the nail produces nail-cells ; epithelial-cells, epithelium, etc. 
When the hand is cut the muscles unite by their own appro- 
priate tissue ; the skin heals in a like manner. When the 
nail is injured the remaining cells multiply themselves, as in 
growth, until the injury is more or less repaired. Remove 
the nail-cells, and the surrounding cells are unable to develop 
themselves into nail. 
Each cell in its development is affected by its environment.—If 8 
The Law of Inheritance ; or, 
the development takes place under circumstances that resistance 
is less in one direction, they may shoot out in this one direc- 
tion, and become elongated. This is well shown by columnar 
or cylindrical epithelium, or by transitional epithelium, asnamed 
by Henle, when the cells acquire points, jags and projections 
in the direction of least resistance, and in the epithelium of 
the skin. Making a section of the skin, we invariably find 
flat and closely-packed cells in the epidermis, with the cells 
on the innermost layer less flattened, and with nuclei. The 
further we advance inward the smaller do the cells become, 
the last of them standing in the form of little cylinders on the 
surface of the papillae; the epidermic cells being an advanced 
stage of growth, in process towards desquamation, the inner 
layers the formative cells, as shown by the nuclei. Patho- 
logically, this law is illustrated by cancer-cells, which, like 
the corpuscles of pus, take their rise from the preexisting cells 
and nuclei of the texture or organ in which the new growth 
originates. 
The influence of environment is conclusively illustrated by 
the study of the development of some fungi, whose spores 
are vegetable cells analogous to the animal cell. 
When the spores of pencillium crustaceum are scattered on 
a substance having the same chemical composition as that 
from which it was taken, a new crop of pencillium crustaceum 
is the result. 
Now, sow these spores on distilled water, and they swell 
up and finally burst, with the expulsion of a great number of 
minute bodies called zoospores, which finally develop into a 
plant which has been named leptothrix. 
If these same spores are put under the surface of a liquid 
rich in nitrogen, the zoospores expelled develop into a micro- 
coccus ; if the liquid is poor in nitrogen, a cypto-coccus is 
developed. 
If these spores are sown in milk, which is a fluid rich in 
nitrogen, we have a micro-coccus appearing, but as the milk 
sours by lactic acid being formed, the zoospores instead of pass- 
ing into a micro-coccus form, change to an arthro-coccus. 
If, again, a pencillium-spore germinates on milk just below 
the surface, we have another form called oidium lactis. 
If, again, a pencillium-spore is sown in fermented wine or The Philosophy of Breeding. 
9 
beer, wherein all the sugar has been converted into alcohol 
and carbonic acid, we have still another form, mycoderma 
acetis. 
Each cell appears to reproduce itself as it is at the time, 
and we thus have development at corresponding periods. The 
fitness of each portion of the body for its present requirements 
is in this* manner secured; and on this principle of a like 
inheritance can be explained the marvellous fact that each 
portion of the body is adapted to its cooperation with other 
portions of the body. Were distant progenitors as powerful 
in their influence on the progeny as others more near, the 
animal, instead of its present harmony of construction and 
function, would be an inharmonious mass of independent 
vitalities. We And, in accordance with this law, that in the 
embryo, parts appear which are fitted for offices and relations 
which are future. If, as appears to be the case, each cell 
reproduces itself, and is also in turn affected by environment, 
it would be in effect a denial of the persistence of force, as 
Herbert Spencer observes, to expect that A can become A1, 
and still produce the same progeny as if it were still A. 
We may have, then, in a cell constant change, with a contin- 
ual reproduction of the original, and thus a definite point may 
be fixed, through inheritance from the past, for each cell to 
acquire those functions for which it is suited. Adaptation, 
therefore, comes through the influence of forces acting in the 
past, and its presence is not only determinate, but is explained 
by philosophy. 
As each cell reproduces itself as it is, including the varia- 
tions brought about by inheritance and otherwise, it seems 
reasonable to suppose that as all the body stands in relation 
of environment to each cell, and produces changes which, in 
turn, are transmitted,—cause and effect, persistence of force, 
irrevocable law,—so the spermatic cell has the power of trans- 
mitting all the inherited variations brought about by the 
totality of the individual, including his past. Inherited 
variation or persistence of force seems a more philosophical 
hypothesis, nay, I will say theory, than pangenesis. 
In those cases of repair after injury, as is noticed by Paget, 
in an adult animal, when a part is reproduced after injury, it 
is made in conformity, not with that condition which was 10 
The Law of Inheritance ; or, 
proper to it when it was first formed, or in its infantile life, 
but with.that which is proper according to the time of life in 
which it is reproduced. In the reproduction of the foot or 
the tail of the lizard, they grow, as it were, at once into the 
full dimensions proper to the part, according to the age of 
the individual. 
Each cell appears to be limited in its powers of indefinite 
expansion, and thus some connection is constantly preserved 
between the early embryotic cell and the future progeny. 
That is, as Paget wTell expresses it, the capacity of assuming 
the specific organic form cannot be communicated to an indefi- 
nite quantity of matter, for undoubtedly there is a consump- 
tion of power in each organization of new matter, and in the 
growth and maintenance of those parts already formed. AVe 
have thus in the primal force a natural limitation. This repro- 
ductive force appears stronger in the young than in the old, 
and it would, therefore, seem as if the formative power is 
more diminished by growth than by mere maintenance. Put 
again, as our author observes, the capacity for the repair or 
reproduction of injured parts is much more diminished by 
development than by growth or maintenance of the body ; 
that is, much more by those transformations of parts by which 
they become fitted for higher offices, than by the multiplica- 
tion or maintenance of those that are already perfect in their 
kind and function’. In other words, to improve a part requires 
more and more perfect formative power than to increase it 
does. 
Changes may originate in a cell from cessation of force.— 
If the cessation be final, we have destruction of form, or, as 
we say, dead matter. If partial, an incompleteness, or a 
check to the development of the new cell may result. 
The forces which originate a cell, and which are contained 
within the new cell, appear to principally affect the devel- 
opment, while growth is largely from forces derived through 
nutrition. This law of cessation of force oftentimes obscures 
the presentation of other laws, especially the laws of sim- 
ilarity. # 
The cell is an entity, containing within itself its peculiar 
forces, derived through inheritance and from its environment. 
The forces must be derived from somewhere, for energy can- The Philosophy of Breeding. 
11 
not be created.* Life is potential,—that is, endowed with 
energy. Its every manifestation proceeds from the utilization 
of force. Inheritance is but an expression of a local fact, 
included in the phrase persistence or correlation, conservation 
or convertibility of force. It can, therefore, be studied iu its 
relations to law. 
Like produces like in the cell; for we have in the new cell 
but another expression of the parent cell, brought about from 
and through the transference of force. As every force acting 
on a cell must produce some effect (for cause and effect are 
correlative, of necessity), we needs have changes produced 
through environment, and tho cell in which these changes are 
produced cannot be the same cell as it was previous to such 
changes, and can, in the line of transference of force, but 
reproduce itself as it is. There must needs be, then, in the 
cell a series of reproductions, in order to gain development. 
As another sequitur, we have limits to the power for repro- 
duction, for work can only bo performed by the use of energy, 
and each change in a cell is an expression of work performed 
or energy used ; and when the changes demanded by environ- 
ment are too great for the remaining forces of the cell, and 
new forces cannot be assimilated from elsewhere, there must 
be a cessation of reproduction, and iu time a destruction of 
form. 
THE SPERM. 
Ill considering the cell, we remarked upon the functions of 
the nucleus as tending rather to the maintenance and multi- 
plication of the cell, than to its specific office. In the sperm 
we shall have occasion to again refer to this important prov- 
ince of the nucleus. 
The semen—or the contribution of the male animal towards 
the generation of offspring—consists essentially of the sper- 
matozoa. Besides this, the product of the testicle, the 
ejected fluid contains the secretions of other glands, which 
probably serve the purposes of dilution for the fluid in which 
the spermatozoa move. Certain it is, from the beautiful 
experiments of Mr. Newport, that impregnation does not take 
place until the spermatozoon actually comes in contact with 
the ovum, and penetrates within its substance. 
* That is, formed from nothing,—an unthinkable proposition. 12 
The Law of Inheritance ; or, 
The spermatozoon differs in aspect in various animals. In 
man it is a perfectly clear, hyaloid, filamentous body, in which 
a dilated portion called the head may be observed, from which 
is prolonged a tail or filament, which generally tapers to ail 
extremity hardly visible from its tenuity. The head, or 
larger extremity, is flattened from side to side, and of a con- 
ical form, the pointed extremity being anterior. The sper- 
matic filament of the bull is somewhat similar, but the blunt 
portion of the oval is anterior, and there is a tendency to 
exhibit a darker anterior and a clearer posterior portion. In 
the rat and mouse the head or body of the filament is uusym- 
metrical and curved. In the common cock the heads are 
oblong and considerably elongated; in the common sparrow, 
wavy. Iu the common perch the spermatozoa exhibit a 
rounded head; iu the river crawfish the filaments radiate 
from the circular head, and are numerous. 
When the spermatozoa have escaped from the male pas- 
sages their active movements commence, and, by the continu- 
ous vibratory or other movement of the filamentous tail, they 
are propelled forward. The tail alone has the power of move- 
ment, and it wisps about with an energy sufficient to move 
many times the weight of the spermatozoon. In the interior 
of the female organs of generation these movements are con- 
tinued for a longer period than in any other situation. In 
the queen bee the capacity for movement is retained for sev- 
eral months after they have been discharged by the drone 
bee; and in the mammalia the movement may continue for 
several after copulation. Leuwenhock points out that 
the spermatozoa of the dog will live or retain their movements 
for more than seven days preserved in a glass tube; and Dr. 
Percy, of New York, reports a case where living spermatozoa 
issued from the os uteri of a female eight and a half days after 
the last sexual connection. In a bat that had been isolated 
for thirty-six hours, both the vagina and uterus were filled 
with spermatozoa in lively movement. 
Even this full development does not, in all cases, seem 
necessary for the fulfilment of the function of the spermatic 
filament. In certain animals, such as the decapod Crustacea 
and others, the spermatic elements are cast forth by the male, 
and are transferred to the organs of the female while they are The Philosophy of Breeding. 
13 
simple cells, which, during their subsequent life, form sper- 
matozoa within the passages of the female, as they would 
have done within the organs in which the spermatic cells were 
first formed, the requisite conditions being duly supplied. 
We will now touch upon the history of the development of 
the spermatozoa, and will thus trace their kinship with the 
cell. In the earlier stages of physiological science they were 
regarded in the light of animalcuhe. At the present time 
they are considered as epithelial cells, or, as Dr. O. W. 
Holmes expresses it, are related to ciliated epithelium. 
They are, as has been before stated, the product of the 
testes. The testicles are a couple of true glands, containing 
the secreting elements in the form of complexly convoluted 
tubules,—the spermatic tubes, or tubuli semenifera}. These 
consist of a fibrous coat, internal to which is a basement 
membrane surrounded by. epithelium. The character of this 
epithelium and the contents of these tubes vary with the age. 
In boys and young animals the slender tubuli contain nothing 
but minute, clear cells, the most external of which may be 
regarded as epithelial cells. The spermatozoa are not found 
in these tubes until puberty in man, and among some animals 
are only developed at certain periods. The epithelium lining 
the tubes is most distinct when spermatozoa are not being 
found, but when the function of the gland is being actively 
performed the tubes are seen to be entirely occupied by cells, 
filled with nuclei, in which the spermatozoa are ultimately 
developed. 
The method of development is thus described by Todd and 
Bowman: "The cells become detached from the basement 
membrane, increase in size, and assume a more spherical form, 
the contents at this time being entirely granules; at length, 
however, several clearer points or nuclei are seen in the inte- 
rior of the cell, which is now passing down the tubule towards 
the vas deferens, while it is succeeded behind by the formation 
of new cells. The nuclei in the interior enlarge, and are 
often seen to contain nucleoli. The parent cell having much 
increased in size from the development of its nuclei into cells, 
appears to undergo no further change ; but in each of the 
contained cells, which vary much in number, one spermato- 
zoon is developed on the inner wall, in the form of a spiral 14 
The Law of Inheritance / or, 
filament, as was first described by Kolliker. The spermato- 
zoon escapes into the interior of the mother cell by the 
rupture of its development cell. Others are in like manner 
set free, and they arrange themselves in a parcel, which may 
ultimately consist of a vast number of separate spermatozoa, 
with all the heads arranged in one direction, and the tails in 
the opposite one.” 
Professor Kolliker has arrived at the conclusion that the 
spermatozoa are not developed in the nuclei of the cells, but 
from them. The nucleus becomes of an oval form, and one 
extremity is elongated to form the tail. 
It is thus seen that the spermatozoon is a living unit which 
originates from within the cell, and appears to be developed 
from the nucleus, which, as we have before stated, seems to 
be the one element of all cells which concerns itself with their 
production ; and as is shown by those cases of cells at emission 
being developed into the spermatic filament in the female 
passages, there is a developmental power inherent in the cell 
after it has become detached from the basement-membrane, 
or, in other words, has changed its appearance but little from 
the ordinary epithelium. The production of these cells seems 
to be somehow analogically allied with the process of gem- 
mation, as in the ideal sperm-cell and the ideal bud. We 
have, at first, a separation from the parent, and, secondly, 
may have the evolving of apparatus to be used in reproduc- 
tion. At this point the resemblance seems to be lost, as in 
the spermatic element there is absolutely required, so far as 
we know, that there shall be a meeting and union with 
another cell to complete the new life, while in the gemmation 
process, the spore itself, as in the female, may develop itself 
into a structure containing organs from which the new gen- 
eration originates. 
This spermatic-cell is allied with the other cells of the 
body, as with the whole body it has been formed through the 
successive development of cells,—simple until after fecun- 
dation. It apparently is primarily an epithelial cell, and it is 
only as the body within which it is found attains age, or, as 
is probable, it is only after cell has reproduced cell for many 
generations, transmitting its own likeness each time with the 
accumulated and accumulating variations, that the spermatic The Philosophy of Breeding. 
15 
filament is formed ; that is, being a highly-endowed structure, 
it can he formed only through successive reinforcements of 
force, or successive developments; that is, it must pass 
through the stated course of heredity with variation. Its after- 
functions, or, as we may express it, the inherent power locked 
up in these minute filaments, in man scarcely one-eight hun- 
dredths of an inch long, indicates high endowments, just as 
the power extracted from a lump of coal is the measure of the 
power which was made latent in the stone form in its pro- 
duction. This is also apparent in the close connection known 
to exist between the nervous system and the organs of gen- 
eration and the physical lassitude following their abuse. This 
close connection between the nervous and generative systems 
explains some of the problems attending the study of inher- 
itance. 
Each cell partakes, it is probable, through inheritance with 
variation, of the changes which have taken place, and which 
are taking place, both mentally and physically, in the body. 
It is a concretion of possibilities derived through a long course 
of vital changes, and which is enabled, under favorable circum- 
stances, to transmit its accumulated powers, through union 
with another cell, to a remote posterity. The hypothesis of 
pangenesis demands the presence of granules or gommules 
which are freely circulating through the system, and which 
are supposed to be transmitted from the parent to the 
offspring, and which can lie dormant or become developed in 
the generations that succeed. To me, this is unthinkable, 
and I prefer to suggest that the law of persistence of force 
requires that no change can take place in a cell without 
changing the possibilities of that cell in its multiplication and 
future development; that each cell is the sum of all the forces 
which have acted on it in the past and are acting in the present; 
that the intimate connection of the generative cells with the 
whole body, arising through their high endowment, stores up 
in them a greater store of possibilities, brought about by their 
extreme complexity of environment. 
These possibilities may be looked upon as forces which are 
modified by every antagonistic force, and, strengthened by 
every force acting in their own direction, only require suit- 
able conditions to become developed or affect development,— 16 
The Law of Inheritance ; or, 
that is, to add forces so as to be changed into other forces. 
In a word, inheritance is but the transmissal of forces, and 
inheritance can be general in respect to the whole body, and 
local in respect to the tissues and parts of the body. 
In the history of the development and in the formation of 
the spermatozoon we recognize a segregation and localization, 
—that is, the putting into form of forces; and when this 
spermatozoon unites with another cell,—the ovum, under 
certain conditions,—a union of forces takes place, and, the 
phenomenon of individual life being thus superimposed, these 
forces are able to accumulate and store up the forces necessary 
in turn for development, growth and future transmissal. The 
whole form and character of the individual is the equilibrium 
of the forces which were united to give him birth, and those 
additional forces added on or influencing during life. If 
we suppose development and growth taking place, or any of 
the phenomena attending vitality, without the corresponding 
expenditure of power, we are involved in an absurdity; for 
appropriation of and transmissal of force, not its creation, is 
consistent with the reign of law, such as modern science 
recognizes as existing. 
In this place it may be well to define our understanding of 
force. It is a power which produces change, or acts to change 
any relations whatsoever between matter,—as the force of grav- 
ity, cohesive force, centrifugal force, vital force. Modern 
science has determined that forces, like matter, are indestruc- 
tible, and that many of them are mutually convertible, and that 
these mutations are rigidly subject to the laws of quantity. 
Every manifestation of force must needs come from a pre- 
existing equivalent force, and must give rise to a subsequent 
and equal amount of some other force. We have laws govern- 
ing force as we have laws governing matter. Every change 
involves expenditure of force. 
As a summary, we may look upon the spermatozoon as a 
cell, the representative of the organism through which it has 
been developed ; as one of the individual unities which are 
freighted with force beyond its own needs, and but requires 
the suited conditions of union with the proper germs under 
suitable circumstances, to develop that force. Just as, for 
illustration, we may consider coal or water as the represent- The Philosophy of Breeding. 
17 
ative of the forces used in their formation. Through the 
destruction of their power, their forces can be liberated to 
again pass into other powers of energy. 
TIIE GERM. 
That portion of the female organism which most nearly 
conforms to the spermatozoon of the male, is the ovum, or 
egg, or, more accurately speaking, the most essential part of the 
ovum, the germinal spot. The germinal spot appears to cor- 
respond to the nucleus of the cell in many respects. The 
germinal vesicle, in which the germinal spot is contained, 
appears a cell surrounded by a mass of nutrient matter known 
as the yolk, and the whole surrounded b}r a vitelline membrane 
or yolk-sac. 
The ovum takes its origin from within the stroma, or the 
cavity of the ovaries, which answer analogically to the secret- 
ing process of the testicle. In many of the lower animals 
the testes and ovaries bear a close resemblance to each other, 
and the same holds good in the early or embryotic condition 
of the generative apparatus of man. In some of the lower 
grades of animals, as generally in the articulates and mol- 
lusks, the ovaries have a glandular character, but in the verti- 
brates the ova are evolved in the midst of a solid fibrous tissue 
or stroma. 
The likeness between the spermatozoa and the ova is again 
indicated by the fact that they both appear to be the product 
of cell-action, with development having taken place after the 
dehiscence of the cell from its companion cells. We thus 
have in the sperm the mother-cell containing the nuclei which 
are formed into ciliated cells, and which are to develop a 
vitality sufficient to support the motion necessary to them for 
the fulfilment of their uses. In the ovum we recognize an 
advanced development, in which the cell containing its nucleus 
is the essence ; the nucleus in both being the essential part 
for the exercise of the complete function of either,—the pro- 
duction of the individual life. 
The ova in women originate in ovisacs or follicles, usually 
termed Graffian vesicles, which are imbedded in the more 
peripheral portions of the stroma. Each follicle in its fully 
formed condition consists of a membrane and contents. First, 18 
The Lcac of Inheritance ; or, 
a highly vascular layer which is united with the stroma of the 
ovary by a rather loose connective tissue. This membrane is 
composed of undeveloped, nucleated, formative tissue, inter- 
mixed with numerous, mostly fusiform, formative cells. 
Second, an epithelium lines the entire follicle, and on the side 
looking towards the surface of the ovary, where the ovum is 
situated, presents a wart-like thickening projecting towards 
the interior and enveloping the ovum. In this germinal 
eminence, as it is called, close upon the fibrous membrane 
of the follicle, and, therefore, in the most prominent part of 
it, is placed the egg (ovulum) imbedded in the cells of which 
the eminence is composed. 
In the articulated and molluscous animals generally the ovum 
is produced from ovaries, which have a glandular character,— 
those of the former retaining a vesicular type ; of the latter, 
often prolonged into convoluted tubes. 
In the ovaries of the advanced foetus and new-born child, 
Graffian follicles are abundant, and the ovum can be seen 
within them. According to Dr. Ritchie, there is a continual 
rupture of ovisacs and discharge of ova taking place even during 
childhood; and I have myself verified this observation in the 
ovary of a calf but a few days old. It is only as the period 
of puberty is reached that the ova are perfectly developed 
and capable of being impregnated. 
The number of ova which may be produced by a single 
animal is immense. In fishes the number is simply incon- 
ceivable. The number spawned by a single cod is stated at 
from one to nine millions. In the herring as many as sixty- 
eiffht thousand six hundred and six ova have been counted 
from one fish. Among animals of the higher orders we also 
have an ample provision. Dr. Barry calculates that the ovary 
of the cow, at the period of puberty, contains as many as two 
hundred millions ovisacs to a cubic inch of the stroma.* In 
the human female the ovary may contain from thirty to one 
hundred follicles. 
In the absence of proof, it seems philosophical to suggest, 
that, judging from analogy, the ovum is directly the resultant 
of cell-action; that cells in the stroma, through a process of 
reproduction, finally arrive at a stage where a certain inde- 
* Todd and Bowman’s Physical Anatomy, p. 818. The Philosophy of Breeding. 
19 
pendence of action can be sustained, and development pro- 
ceeds, aided by the actions going on simultaneously in the 
surrounding cells, producing changes on them, and having 
changes produced in them in turn on themselves. The existence 
of and discharge of ova during childhood, and the incomplete- 
ness of the organization of such ova, by which impregnation 
is rendered impossible; the existence of the nuclei, which 
suffer less change, or resist changes longer than the cell; 
the formative power which the cells of the ovary appear to 
possess even after the extension of the ova, as witnessed in 
the corpus lecteum ; the numbers of ova beyond all seeming 
needs ; the appearance of the germinal vesicle first in the order 
of development, and the analogy between the sperm and the 
germ in their development, are all suggestive of this view. 
In the preparations for fecundation the mother-cell of the 
testes possesses nuclei which develop into spermatozoa and 
are scattered as animated particles within the secretions 
of the seminal tubes. In the ovum, as a preparation for 
fecundation, it seems probable from the observations of many 
skilled observers, that the germinal vesicle is dissolved (like 
the mother-cell), and the diffusion of its contents (which 
originate or are formed from the germinal spot or nucleus) 
through the yolk, which may be considered in some sense a 
secretion. 
Certain it is that the ovum, like the spermatozoon, repre- 
sents vitality. A period in its development arrives when it 
becomes capable, under fit conditions, of establishing an indi- 
vidual and independent life. This condition of vitality may 
remain for a considerable, though uncertain, period of itself; 
the ovum has reached the highest development that it is ordi- 
narily capable of, and it requires for its future development a 
set of conditions external to itself, the union of the fecundat- 
ing germ and tit surroundings. 
This ovum is, however, tilled with possibilities. It con- 
tains, as does the sperm, elements which may go to make up 
an individual and independent life, and is one of the connect- 
ing links which unite all the vital forces of the past with 
future generations. It is a vehicle for the transmissal of the 
forces which have had part in its own evolution. 
Each cell or completed ovum contains its own forces, which 20 
The Law of Inheritance ; or, 
cannot be alike in each, such is the complexity of environ- 
ment, but which can approximate in likeness according as the 
conditions of their evolution have been more similar. MVe 
cannot expect that in the continual development of ova into 
new beings—although the conditions of the environment of 
the development brought about by fecundation may be very 
similar—parallel results shall in any case be obtained. In the 
case of brothers and sisters we usually see resemblance, never 
exact likeness of form or character,—occasionally an unlike- 
ness of form or character. In twins it is a matter of constant 
observation that the resemblances are usually quite close. 
In the latter case, where the conditions of fecundation are 
alike, and the development of the various germs which make 
the new being are somewhat cotemporaneous in the time of 
their development, and consequently exposed to a somewhat 
similar environment, such differences as we observe between 
the two offspring are to be largely explained by the difference 
in the forces which were contained in the germs. 
The ovum, like the sperm, being a representative of a con- 
crete force, which has been made up from the action and reac- 
tion of all acts affecting past ancestors which have had any 
effect on its development, it must follow, as a matter of course, 
that any individual act affecting the development of these 
cells, must likewise be represented in the modifications pro- 
duced in the forces which, through the ovum, are transmitted. 
On this view we can explain the action of imagination, or 
of a previous impregnation, upon the offspring. A long con- 
tinued or a violent impression on the nervous system through 
the changes following every act through which there is a con- 
sumption of force, would necessarily modify, in some form, 
the development of cells whose functions are peculiarly those 
of transmissal. The fact that the development of the ovum 
in woman is checked for a time, during the presence of the 
child in the womb, and to a certain extent during lactation, 
indicates the close relation between the germ expelled and in 
process of development and the cells of the stroma of the 
ovary. The sympathetic and nutritive relations are undoubt- 
edly quite close, and the forces of the one are being modified 
through the presence of the other. Such a change may, per- 
haps, be recognized in the progeny, it depending on our The Philosophy of Breeding. 
21 
ability to more or less readily discern such changes as may 
have occurred. 
Animals, by food, not only maintain the perfect structure 
of the body, but also lay up in their tissues a store of power 
for future needs. The power stored for the individual is 
latent for a time, but reappears and becomes active when 
required, in the resolution of once living structures, by the 
vital processes. The force required for the purpose of the 
germ is derived from the progenitor; as the germ changes its 
condition it may derive force through its own development, 
just as the body renews its force through its development. 
When the force derived from the parent is insufficient for the 
continuation of the development process to a self-supporting 
condition, that is, to individual life, the germ must perish. 
Consider how few germs of the millions contained in the 
cow’s ovary which can ever arrive at a stage when there is a 
capacity for receiving fecundation. 
The primal force—or the force existing at the origin or first 
recognition of any of our animals—need not be so inconceiv- 
ably large. It is not requisite to suppose, with Prof. Huxley,* 
that in the case of the successive viviparous broods of aphides, 
a germ-force capable of organizing a mass of living structure 
which would amount, as it has been calculated, in the tenth 
brood to the bulk of five hundred million of stout men, must 
have been shut up in the single individual, weighing possibly 
one one-thousandth of a grain, from which the first brood was 
evolved. The force transmitted is but that which has acted 
on and influenced the transmitting cell, and this cell, under 
unsuited conditions of development, perishes, and the force is 
resolved into other forces; or, under suitable conditions, the 
cell establishes a vitality independent of the parent, with the 
possession of sufficient force to enable it to add to the forces 
already possessed, in the way established by natural law. 
To understand the germ-force of the case of the aphides under 
consideration, we must conceive of the force transmitted to 
be at least that sufficient for a singlo individual, and each 
individual to elaborate through natural agencies a sufficient 
power for its own growth and development and for transmissal 
to its brood in turn. It but transfers a portion of that force 
* Organic Reproduction of Aphis, in Tenis. Trans. Vol. XXII., p. 215. 22 
The Law of Inheritance ; or, 
which itself possesses, and which, through natural processes 
of development, is segregated from the parent for the purpose 
of the new individual. The parent, through the vital proc- 
esses, continually renews and increases the original develop- 
mental force through nutrition and other circumstances of 
environment. The brood from this parent do likewise, each 
individual for itself. Deprive this group of aphides of all 
nutriment whatsoever, and how far could the developmental 
forces continue? 
The germ and the sperm have many points in common, 
and, as shown by the history of their development, are 
undoubtedly but ditferentiated products of the same funda- 
mental element—the cell. According to the law of persist- 
ence of force, the creation of a new product cannot be a 
forming from nothing, but a transference only of force or 
forces, form or forms, already existing. The germ and the 
sperm cannot contain an original germ-force which of itself is 
sufficient for all futurity, for such a proposition is simply 
unthinkable. The forces which the germ and the sperm 
transmit can be what they have, no more nor less. 
The germ and the sperm, therefore, contain not the total 
force and all the forces which are to act during the life of the 
product, but they do possess the forces necessary to originate 
the new being and influence the development in certain lines, 
and the capacity of adding to these inherited forces according 
as opportunity offers. When the forces are insufficient for 
these purposes the product dies. When the operations ot 
these forces are misdirected by circumstances,—that is, a con- 
flict with other forces, or checked, or accumulated in one 
direction, or neutralize each other either wholly or in part,— 
changes ensue; and it is this fact, this application of the law 
of persistence or indestructibility, which explains evolution and 
insures progress in the development of individuals and races. 
The forces derived from heredity, and the effect of nutritive 
forces on their development, have a dependent influence, not 
only in the parent, but during the whole life of the germinal 
product. 
GENERATION. 
Iii some of the lower organisms the egg may be sufficiently 
organized to continue its development without the added force The Philosophy of Breeding. 
23 
received from the sperm. This is the case with some butter- 
flies, and most notably in the case of the queen-bee, whose 
eggs, produced under circumstances that forbid the suspicion 
of fecundation, can and do advance towards maturity and 
develop into the completed insect—the drone. In this instance 
we seem to have the gemmiferous method of reproduction in 
quite highly-constituted insects, whose continued existence is 
dependent on the oviparous or true generative process. 
In reproduction by division, we seem to have a tendency 
towards a weakening of the germinal capacity, as is indicated 
by the consideration of those lower forms of vitality in which 
the process of nutrition and reproduction are more clearly 
dependent on each other. Thus, limitations of growth and 
arising through age indicate a decrease of germinal energy in 
the reproduction of cells in the tissues, as also does the con- 
verse fact that repair of injuries takes place with far greater 
completeness and energy in the young than in the old. In 
organisms that multiply by the fissiparous and gemmiferous 
method, there is usually, if not universally, some provision 
made for the occasional formation of new beings by the process 
of fecundation, or of union with distinct cells. 
In the plant and in the simple animal life we find a homo- 
geneity of structure, which has but comparatively few special- 
ized functions for its cells. Like those parts of the tissues of 
higher animals which readily undergo repair, these cells are 
formed mostly through nutritive repetition, and the forces 
which regulate development appear quite simple in character 
and evenly distributed throughout the whole cell-structure. 
Thus the polype may be divided and subdivided, and each 
portion will develop into a new polype. The twig removed 
from the plant may form roots and develop itself into an 
individual plant like the parent stock. 
It will be seen that the functions of nutrition and repro- 
duction are, in one sense, allied. They are both dependent 
for their origination and for the carrying out of their functions 
upon a force derived external to themselves. In the fissipa- 
rous method of reproduction we recognise the process by 
which both the cells of animal tissues may be formed and 
the origination of independent individuals among the lower 
organisms. In the gemmiparous method we have an instance 24 
The Law of Inheritance ; or, 
iii the ova of the queen-bee, and in the preceding section we 
have shown that the ovum is in essentials an animal cell. The 
connection between the gemma and the cell may not be so 
well indicated in some cases as in the hydra, where the gemma 
thrown off are not merely structurally, but functionally com- 
plete ; but it is clearly indicated in the zoospores of an ulva 
or conferva, where the gemma appears but a cell, yet has the 
inherent capacity of development into the parent species. 
The act of generation is but the union of two cells, the 
sperm and the germ, whereby a new being is the result. The 
process in itself is not different in its principles from the other 
methods of reproduction, but differs in the results following 
its application. In all cases the only requisite for reproduc- 
tion is the presence of a sufficiency and variety of force to 
originate and support the process we call vital. In simple 
cells there seems to be this force present, apparently in a ratio 
with the age of the cell. As we attain complexity of envi- 
ronment for certain cells the forces at work, or sufficient for 
reproduction in the simply-constituted cell, are in part used up 
in meeting and responding to the changes produced by added 
complexity, and less is available for the production of new 
cells like themselves, and reproduction is retarded in propor- 
tion as demands are made on the vital forces for other pur- 
poses. This antagonism between the nutritive (self-preser- 
vation) and the generative (self-propagation) functions has 
been generally remarked upon by physiologists, and is to be 
explained by the doctrine of persistence of force. 
When the force inherent is sufficient for preparing the cell 
for development, and yet cannot compel the development 
further of itself, on account of the weakening of some of its 
forces through expenditure in sustaining the equilibrium 
between itself and other forces, we may have reproduction by 
gemmation, the cell cast forth meeting with new forces in its 
career, which its inherent vitality enables it to appropriate for 
its own use, and through the added force extend its own 
development. Thus the egg of the queen-bee cannot hatch 
the drone except)* food be supplied it; and the force within 
the egg when laid only enables it to develop the grub, a par- 
tial transformation towards the completed insect, for the pur- 
pose of appropriating and using the forces stored in the food The Philosophy of Breeding. 
25 
and necessary for the completion of the development. The 
female, egg—or that which receives fertilization from the 
drone—is in possession of an added force, which enables it, 
in the presence of suitable food, to acquire unto itself the 
forces necessary for development into a worker, or even into 
a queen-bee. 
In the higher animals we find the process of reproduction 
by generation universal. In other words, so great is the 
complexity of their environment, and so complex is their 
structure for meeting the changes brought about by this very 
complexity, that we find the various parts and organs of the 
body highly specialized. As a resultant therefrom, we observe 
but a limited repair even to the tissues of the body, and this 
repair far more common in the womb and during childhood 
than in old age. The generative organs are highly special- 
ized, as they are fitted through long-continued inheritance, 
with variation arising from the persistence of past and present 
impressions, for the transmissal of those qualities with which 
they have or may be impressed. The force inherent, how- 
ever, is insufficient, or not of the right quality, of itself, in the 
male or female cell, to advance further development than the 
stage in which we find it. By the union of the two forces 
we have a sufficiency to overcome the difficulties, and a further 
development may take place. 
This statement is illustrated by the experiments of Gartner, 
who, after making successive trials on a malva with more and 
more pollen grains, found that a few grains of pollen did not 
fertilize a single seed; that enough pollen might be added to 
form a few seeds of small size, while a sufficiency would pro- 
duce the full development. Naudin followed the same line of 
investigation with the mirabilis, in which the pollen grains 
are large and the ovarium contains but a single ovule. A 
flower was fertilized by three grains and succeeded perfectly; 
twelve flowers by two grains, and seventeen flowers by a 
single grain, and of these but one flower in each lot perfected 
its seed ; and it is worthy of notice that the plants produced 
by these two seeds never attained their proper dimensions, 
and bore flowers of remarkably small size. 
In the ingenious experiments of Mr. Newport upon ova of 
amphibia, it is shown that the contact of a single spermato- 26 
The Taw of Inheritance ; or, 
zoon is not adequate to produce complete fecundation; but 
that the penetration of a certain number of spermatozoa is 
requisite, and that fecundation may be effected partially, so as 
to occasion some of the developmental changes, by a small 
amount. 
That in development or generation the initial stage is merely 
the addition of certain forces, is also indicated by the obser- 
vations of M. Jourdain, that out of about fifty-eight thousand 
eggs laid by unimpregnated silk-moths, many passed through 
their early embryonic stages, thus showing that they had a 
capacity for a certain amount of development, but only twenty- 
nine out of the whole number produced caterpillars. In this 
case, had the germ-force of the egg been increased by the 
force added through the process of fecundation, it cannot be 
doubted but that the caterpillars would have been far more 
numerous. 
Darwin remarks that the belief that it is the function of the 
spermatozoa to communicate life to the ovule seems a strange 
one, seeing that the unimpregnated ovule is already alive, and 
continues for a considerable time alive, and, as we will add, 
is capable of a continuous development for a limited extent; 
limited largely by race and species, but to a certain extent iii 
the individual. 
Every consideration that I can bring to bear on my own 
mind seems to point to the truth that generation is but a form of 
the accumulation of forces to produce a certain result in exact 
accordance with the forces that take part in the process. If 
the forces become deficient for this purpose, then development 
is modified or ceases at just that point where the insufficiency 
shows itself. If the forces designed to be stored in the two 
germs, or even in either singly, are diverted from their legiti- 
mate purpose of reproduction, then failure, partial or com- 
plete, will result, as is illustrated by the seed, which, if 
secluded from the free access of air and moisture and kept 
under other suitable conditions, in order to prevent the expend- 
iture of force,—that is, change,—will preserve its vitality for 
a long time. Allow, however, the access of air or moisture, 
or other condition which will induce change in the seed, the 
vital force is expending itself in resisting these changes—that 
is, forces ; and the environment not being suited for growth,— The Philosophy of Breeding. 
27 
that is, the adding as of additional forces,—we have in the seed 
either a noticeable decay or a complete loss of vitality, or 
such an insufficiency of vitality that the growth can be but 
feeble and partial, even if suitable conditions for its growth 
and development are now presented it. Among our domestic 
animals we have additional illustrations in the effects on fecun- 
dity following insufficient feeding, full feeding and, perhaps, 
over-feeding. Among the Arabs a year of scarcity is said to 
be followed by one of almost complete barrenness among their 
flocks ; and all breeders of sheep are aware of the importance 
of abundance of food in influencing the production of twins. 
Generation is the actual contact of two peculiar cells and 
the union of their forces. On the sufficiency or insufficiency 
of these forces, and on the relative quality of the concrete 
force presented by the one parent or the other, depends very 
much the future progeny. The changes following the union 
of these two generative cells naturally fall under the head of 
development, for with the conjunction of the two forces the 
act of generation is accomplished. 
DEVELOPMENT. 
In the sperm we have a development taking place in the 
mother-cell and in the nuclei, but this ceases with the forma- 
tion of the spermatozoon. It is the function of this cell to 
add force, and influence other creations. In the germ, on the 
contrary, we have a development going on to an almost 
unlimited degree. The mammalian ovum is, at the time it is 
fitted for fecundation, far beyond the simple cell in complex- 
ity. It contains various contents, granular in form, and dis- 
tinct membranes enveloping these and the primary cell and 
its nucleus,—the vesicle and the germinal spot. The ova of 
various insects, as remarked with reference to the silk-moth, 
can develop into intermediate embryonic forms quite gen- 
erally, while a very small fraction can continue to the extent 
of the completed caterpillar. The function of the ovum is, 
therefore, to receive forces up to the extent sufficient for its 
development into the state in which it can maintain of itself 
its equilibrium with its surroundings. 
Parthenogenesis, or the alternation of generation, seems a 
striking instance of this law of development. The whole 28 
The Law of Inheritance ; or, 
phenomena may be considered in the light of incomplete 
development, on account of the deficiency of primal force 
which it is necessary for the germ to add to, through the 
process of vitality, before sufficient force can be accumulated 
for the production of the completed form. Thus the fern 
sends forth a spore which is but an incomplete development 
which obtains and elaborates its own nutriment, until it 
accumulates sufficient force for the carrying forward of the 
true generative act, which results in the formation of the 
new fern. 
In so-called arrest of development, it is usually noticed that 
the defect resembles the same part at an earlier period of 
embryonic life, so that although growth may have continued, 
yet it has not developed beyond the grade which it has already 
attained in embryo. This is but another illustration of the 
persistence of force ; the inherent power which influenced the 
continued advancement of the part was deficient, and hence 
there could be no progress. As the body is but the balance- 
ment of all the forces which have taken part in its past 
history, defects of a character which indicate cessation of 
force are useful guides towards the study of the past history 
of the race, or, in other words, the progress of evolution. 
It is, perhaps, the place to define what we mean by the 
term "development.” It is the word by which we express 
the process through which a tissue or organ is formed, or by 
which a tissue or organ or cell is changed so as to be fitted 
for maintaining its relations with a more complex environ- 
ment; that is, fitted for a higher function. It is not growth 
or mere increase ; it is the acquiring not of greater bulk, but 
of new powers and structures which are adapted to higher 
conditions of existence. The forces influencing development 
and growth appear to be of a different intensity and charac- 
ter, yet, under certain circumstances, seem mutually convert- 
ible each into the other. 
Death is the limitation to the power of development. When 
the demand upon a cell or a life is beyond, the power of that 
cell or life to respond, we find retarded development, or, as 
it is generally called, disease, which must end fatally unless 
the demands can be lessened or the power of the cell or life 
increased. When the cells of the body have exhausted their The Philosophy of Breeding. 
29 
primal force derived through inheritance in the process of 
development and nutritive repetition, then decay is but a 
question of time, for without renewal there can be no lasting 
continuance ; for force cannot be created—it can be only appro- 
priated through changes of matter. 
The ideal cell repeats itself through the force which is 
stored within it. As forces have been received by the parent 
cell through nutrition, and as force must have beeij used by 
this cell in the support of the processes which accompany 
vitality, this cell cannot transmit itself, as itself was when first 
formed, to its own offspring, but transmits those forces only 
which itself possesses at the time of the generation or produc- 
tion of the offspring. Each cell, it is thus perceived, possesses 
within itself the concrete force received from its progenitors, 
and the additional or lessened force brought about by the 
circumstances of its own environment, the sum being the 
concrete force to be in turn transmitted to its own descend- 
ants. As the environment increases in complexity there is a 
constant demand upon the cell for changes sufficient to enable 
it to meet this new condition of affairs. If there is not enough 
force to the cell to respond, it languishes and perishes. If 
the force is sufficient to enable the cell to meet the new 
demands, development follows. 
From these remarks will be inferred what the process of 
development indicates to observation, that progress is in the 
line within which, and in the sequence through which the 
forces which make up the concrete force was received. Each 
cell has, therefore, if not interfered with by environment, a 
primal force which rules at what successive development any 
change must take place; for if our views are correct, each 
change must be influenced by the change which has pre- 
ceded it. 
Growth is distinct from development, and does not require 
such a high vitality, or impressed force on the tissues, which 
compose the substance of the part which is to receive it. A 
force, therefore, which may be insufficient to continuously 
develop a portion may be sufficient to preserve form and 
function unchanged for a time at the extreme limit of the 
power of the developmental forces, and even to produce 
increase of bulk, as is so well shown by those cases of arrested 30 
The Law of Inheritance ; or, 
development where the size remains, hut the structural plan 
is that of a lower grade of animal life, as in malformed huofo, 
where development makes no progress, hut the growth goes 
on to beyond the ordinary bounds. 
Let me enunciate a few general laws which may be deduced 
from what is thus far written. 
Each cell contains its proper formative force which deter- 
mines its future. 
The force contained within each cell may be increased or 
diminished through its environment. 
Each cell receives its development to such an extent as is 
determined by the forces which it has or may receive,—no 
more, no less. 
Complexity of environment requires in the cell a greater 
force of resistance and more changes, in order that an equilib- 
rium may be established, than simplicity of environment. 
The order or sequence of development is the same as that 
in which the force which determines the development was 
received. In other words, persistence of force requires an 
evolution, a progress onward so long as increased complexity 
of function is required, and the forces appropriated are suffi- 
cient to establish the equilibrium; and the law of inheritance 
requires that the force shall act in the order in which they 
were received, for the sum of the past forces is essential to 
the formation of the new concrete force. 
The general law of matter, that like causes produce like 
effects when acting on the satne material, also finds expression 
in this connection. This is illustrated by symmetrical diseases. 
As Paget remarks, the morbid substance in the blood, "fastens, 
for instance, on certain islands on the surfaces of two bones, 
or of two parts of the skin, and leaves the rest unscathed, and 
these islands are the exactly corresponding pieces upon oppo- 
site sides of the body. The conclusion is unavoidable, that 
these are the only two pieces that are exactly alike ; that there 
was less affinity between the morbid material and the osseous 
tissue, or the skin, or the cartilage, close by, else it also would 
have been similarly diseased.” If we understand by affinity 
the expression in a partial form of this law of forces, the 
matter is rendered more intelligible. The like portions of 
the body, the symmetrical ones, are developed through like The Philosophy of Breeding. 
31 
forces, and have like powers of resistance to the morbific 
element. 
The more highly organized the structure the longer it seems 
to take for arriving at full maturity. Thus puberty, brain- 
cells, etc., illustrate. The process through which maturity 
arrives is through a series of constant changes and constant 
advancement. We all recognize this element of time in the 
growth and changes of function in the young; it is also con- 
clusively illustrated by the well-established law of inheritance, 
through which there is a tendency to inherit at a correspond- 
ing age. 
There also seems to be an antagonism between the processes 
of growth and development, as has been before remarked on. 
This is but an expression of the fact that forces utilized in 
one direction cannot, at the same time, be utilized for another 
purpose. 
If such be the genesis of the progress of cells towards 
higher capabilities, the same laws must hold true for the com- 
pleted life—the animal—the harmonious aggregation of these 
unities and their results. 
Going back to the egg, we will trace somewhat of the 
development, as illustrated by the mammalian ovum. The 
organized ovum receives additional force through the conjunc- 
tion with the spermatozoa, and is now enabled to proceed 
with changes in accordance with its capabilities. 
The egg consists of a membranous external sac or envelope, 
inclosing the spherical yolk, within which is the germinal 
vesicle and its nucleus. The nucleus, or the germinal spot, is, 
as we have heretofore said, the spot where is the life, or the 
power of originating the life. The yolk, however, has a most 
essential share in the development of the embryo. It may be 
considered as the contents of a cell of which the germinal 
vesicle is the nucleus, if we regard this more completed stage 
of development as a single cell, as it is claimed to be by 
Schwann. 
The fertilized—that is, strengthened—ovum in a short 
period commences to show changes. According to Barry, 
the immediate effect of fecundation is to cause the germinal 
spot to pass to the centre of the vesicle and the vesicle to the 
centre of the yolk. The spot first indicates a change, which 32 
The Law of Inheritance ; or, 
is a mark that fecundation has taken place. After a short 
time the germinal vesicle disappears, and is succeeded by two 
cells. Each of these twin cells gives origin to two others, 
making four. Each of these four in turn gives origin to two, 
by which the number is increased to eight; and this mode of 
augmentation continues until the germ consists of a mulberry- 
like object, the cells of which are so numerous as not to admit 
of being counted. Together with the doubling of the cells 
in number has been a diminution in size, and each cell is 
found filled with the foundations of new cells into which its 
nucleus has been resolved. 
From this germ the embryo begins to be formed. There 
is a separation into a defined central and peripheral portion, 
both of which at first appearing granular, subsequently are 
found to consist of vesicles. This mass becomes in turn more 
and more differentiated, and we have an appearance which has 
been described as the primitive streak, and a little further in 
time the dorsal laminae. Thus the development proceeds, 
constantly showing greater changes and more differentiation 
of structure. 
At first the development indicated is that of the lower 
animals, as of the fish ; then that of the reptile, the bird, the 
mammal; then to the species,—variety,—and afterwards to the 
individual. The progress is from the simple to the complex. 
It will not be understood that the human embryo is at one 
time a fish, at another time a reptile, etc. He merely assumes 
the same type of structure that the bird or reptile assumes in 
their developmental state.* 
It is accordingly seen that a full development of a part 
into a completed structure is a complex process, in which the 
forces are changed and are changing constantly, and only after 
a steady continuance of developmental changes can finally 
possess the force of the strength and character fitted for the 
succeeding structure. The force sufficient to develop the fish 
or reptile is insufficient to develop the man; and when the 
force is at that point of accumulation, through inheritance and 
otherwise, that its strength and direction is in any way equiva- 
* For an illustration of this community of structure, as shown by development, see 
Darwin’s “Descent of Man,” Yol. I., p. 15, where drawings of a human embryo and 
of an embryo dog, at about the same stage of development, are contrasted. The Philosophy of Breeding. 
33 
lent to somewhat the samo force used in the development of 
another animal, there must needs be shown a resemblance. 
Persistence of force, therefore, shows a necessity for the belief 
in the gradual evolution of one type from another, in all cases 
where conditions of life are becoming more complex. 
At the birth of the young being development does not cease. 
The parts are continually gaining in power, and are‘changing 
in form throughout the period of youth. As the infant 
increases in age he develops more capabilities, either through 
the perfection of old or the formation of additional structure. 
As the forces decrease in intensity the child—now become a 
man—is said to bo growing old ; and when the forces give 
out, then development ceases ; there is no capacity for the 
gathering in of the power that is necessary to supply the 
force consumed in the labor of living, and death ensues. 
Partial failure to meet this equilibrium may produce disease 
only, and the patient, by gradually regaining this equilibrium 
between expenditure and supply, may recover his health. 
Life and death, development, reproduction, generation,— 
all are the expression of the effects under general laws, of 
which that of persistence of force is the chief. Inheritance 
is shown in development, as in ovulation and generation. It 
is but the expression of facts of our observation; and it is 
by the study of development that we are able to assert that 
heredity is an expression of the action of general law—per- 
sistence of force as applied to vitality;—a law so powerful 
and universal in its conception, that once given vitality and 
constant change of environment, and if vitality endures, devel- 
opment must of necessity ensue. In each, cause must produce 
an effect, and we thus have change. In the change we cannot 
conceive of no effect following the altered circumstance, so 
that neither the cells nor their concretion, the body, after 
once having undergone a change, can transmit the same 
qualities or forces that they could have done if unchanged. 
By the same law, transmissal or development of forces can 
only take place in accordance with the order in which they 
were received, for force modifies force; and no concrete 
force could be just what it is had there been any change 
in any of the individual forces, whose totality is the result 
before us. 34 
The Law of Inheritance ; or, 
There seems a difference between the force utilized in 
growth and that utilized in development. It is of a more 
siitiple power, on account of more simple requirements. 
Development appears to be dependent more on the primal or 
inheritable force than growth, which is derived principally 
from the forces acquired during life, as from food, etc. The 
two methods are, however, in large degree interchangeable. 
The essential element of growth is the reception and adding 
on of new material, whereby bulk is obtained, or a nutritive 
repetition. Growth and development are usually coincident. 
As an illustration of growth without a corresponding devel- 
opment, wo have the malformed heart. Among the collec- 
tions in the museum of the Royal College of Surgeons, writes 
Paget, one among them presents only a single cavity ; no par- 
tition has been developed between its auricles or its ventricles ; 
it is, in respect to its development, like the heart of a foetus 
in tho second month ; but though its development was checked 
thus early, its growth continued, and it has more than the 
average size of the hearts of children of the same age. 
In the cell, growth may be manifested in the increase in 
surface or thickness of the cell membrane, or the c.ell departs 
from its primitive globular character in such a manner that the 
cell membranes only add new substance and extend out two 
or more points. The membranes may become thickened or 
changed through an infiltration or deposit of hard substances, 
which may add bulk, or the cell may also divide and form new 
cells, and these in turn others, while the part necessarily 
increases in size through this increase of cells. In this case 
we may have growth to the part and development to the cells. 
We see instances of this process in the whole history of foetal 
and early life. In adult age we may have increase of a part 
through exercise, which result is usually an indication of 
health. We may have, moreover, growth and development 
coexistent in the adult in some cases, which are pathological, 
as in those cases of hypertrophy in which the enlargement of 
a part is effected with increase of its natural tissues, with 
proportional retention of its natural form, and with increase 
of power. 
GROWTH. The Philosophy of Breeding. 
35 
This increase through excessive cell action is, of course, 
from this doctrine of persistence of force, more or less inher- 
itable. We are not surprised, therefore, tcxfind instances of 
transmission of obesity in families, or of strength, or of pecu- 
liar traits, involving an excess of activity of cell action, as 
mental inheritances, inheritances of milking qualities in the 
cow, etc. When the action of growth is accompanied by the 
action of development, it seems probable that the force is of 
a more perfect character than is the force requisite for growth 
alone. That is, a force sufficient for growth may not be suffi- 
cient or of the right quality for influencing and carrying for- 
ward an extended development. When a force is insufficient, 
we should expect either a partial or complete failure, and also 
that the exact form in which the failure should come about 
would vary according to the circumstances affecting it. We 
can thus theorize on those cases where parents of the ordinary 
sizo have given birth to dwarfs and to children of ordinary 
size. A force insufficient for development should bring about 
an abortion, or a failure in the offspring acquiring that degree 
of existence in which the vital powers are able to add the 
forces requisite for completing the process for arriving at 
maturity. A force insufficient for a vigorous growth might, 
under peculiar circumstances, allow the developmental forces 
to continue in the formation of the young. Durdach cites an 
instance of one man who had eight children from the same 
wife, of whom four were dwarfs ; and Prosper Lucas another, 
where of six children two were dwarfs. 
Developmental and growth force, however allied, and how- 
ever much they may influence each other, yet appear to have 
this essential difference : growth is the absorption or gaining 
of power through a direct increase or gain arising through the 
presence of additional force, which is appropriated under the 
influence of the developmental force. A process in its concep- 
tion simple, developmental force is a concrete force, brought 
about through complexity of environment, and its existence 
depending largely and primarily on forces accumulated in the 
past. As a summary, growth and developmental forces are 
alike controlled by their past history, viewing the forces con- 
trolling each at any particular moment as a concrete force; 
but the forces which regulate growth are increased more 36 
The Law of Inheritance ; or, 
readily by a certain form of environment, nutrition, than are 
the developmental forces. Development is a higher form of 
force, and is at further remove from,the inorganic than 
growth. To repeat, the process of growth is far more under 
the sway of nutrition than is that of development. The 
ill-nourished plant may develop during growth, but the 
growth is stunted. The rag-weed of our gardens can be cut 
to the ground, and be exposed to great extremes of drought 
on a gravel knoll, yet if there is vitality left, it will bloom 
and ripen its seed, with an extremely scanty growth. This 
plant, in a rich and congenial soil, may be three feet tall; 
under adverse circumstances the same process of development, 
in kind, may take place in a plant under two inches tall. 
We have, in growth, an unknown though probably deter- 
minate limit. Up to that limit growth can be accelerated, 
and even forced, by nutrition. Within limits growth can be 
retarded ; even a diminishing of bulk can take place through 
the withholding of nutrition. Growth influences development; 
but no amount of growth,—or, in other words, the presence 
of unlimited nutrition,—apparently, affects development but 
in very circumscribed limits. The conception of growth is 
simple,—accretion, as a crystal, may be said to grow from the 
deposit of its own material from the surrounding menstruum. 
The conception of development is complex, involving an 
adjustment of many forces, operating through long periods, 
and includes growth. 
Growth is distinct from development, yet allied; is deter- 
mined under the directions of the same laws which govern 
development; yet the forces which determine growth and 
development are different, in the same respect as are different 
the forces which determine different exhibits of development. 
All vital processes are the footing up of an unknown column 
of figures that go back to the beginning. Every unit tells, 
and some are plus and others minus. The phenomena we 
observe is their addition, and the integer is fixed, although 
perhaps not determinate to us. These integers are different 
in every case. Higher in development than in growth, and 
the tendency to increase according to the number of units 
furnished through an increased complexity of environment. 
Growth is in sequence before development, as it is depend- The Philosophy of Breeding. 
37 
ent on simple causes ; for the law of all nature is from the 
simple to the complex, rather than from the complex to the 
simple. 
SUMMARY. 
The laws of breeding may be likened in their development 
to a tree. First the root, then the trunk, branches, twigs 
and leaves. The root represents law,—the law of causation,— 
or, as it may perhaps bo called, the law of unity,—tho law 
which directly preserves the harmony of all nature. This 
primal law is the idea, which, as a conception and as a fact, 
is the support of all processes of thought, whether of induc- 
tion or deduction. The trunk stands for the conception 
expressed by the term persistence of force (a law scarcely of 
less universality than that of causation), because on it are 
built up all tho rest of the parts united with and flowing from 
it. Tho limbs represent in turn subordinate and connected 
laws,—such as those of resemblance and variation. The 
twigs, other laws still more subordinate to the rest,—such as 
find expression in the terms reversion, prepotency, etc. The 
loaves can bring to mind the laws directly affecting the species 
and the individual. 
We might use in illustration a figure calling attention to the 
gradual succession and inter-dependent position of laws, whoso 
understanding constitutes the science of breeding, the whole 
structure passing from the periphery of individual facts 
through successive gradations of deductions, in which the 
facts reappear in successive integers, until all observations 
unite into a completed aggregate, and give conception of and 
expression to the law founded in nature available for this 
development or evolution. 
In our several divisions wre have traced the law of persist- 
ence of force, as well as regarded the law of unity, by con- 
sidering in turn those parts and functions which take part in 
the formation and evolution of the adult life. We have shown 
that the germ and the sperm-cells have a development analog- 
ically parallel, and that they are governed in their develop- 
ment by the operation of the same laws. We have attempted 
to show that, in generation, we have but an expression of the 
same laws which operated to procure the elements essential 
to it. That development and growth, the sequelae to genera- 38 
The Law of Inheritance ; or, 
tion, are governed by precisely the same laws, bearing in 
mind throughout the effect of complexity produced by envi- 
ronment, and the influences predicated on the general laws 
involved. We have thus hoped to have established the con- 
nection of the law of persistence of force with vital operations, 
and its importance as offering an explanation for all the facts 
involved in the consideration of evolution. 
Biological science is under the control of those great laws 
which regulate the cosmos, and the law of the persistence of 
force is the chain which, permeating life in all its branches, 
links its phenomena with those of the universe. Evolution is 
not the cause of changes of animal forms and instincts; it is 
not merely an expression of the observed facts of animal 
advancement; it is an expression of the process of develop- 
ment under the law of persistence of force. When this beau- 
tiful law is once apprehended, there can bo no escape from 
the deductions which are seen to flow directly from it. 
In studying the phenomena attending the breeding of 
domestic animals, we have in this law the key for the investi- 
gation of the observed changes, and the science of breeding 
is established. With study and observation all practical 
details which are precisely apprehended .can be seen to be so 
connected with previous and existing phenomena, through the 
expression of this law of persistence, as to constitute a science ; 
for science is nothing more than the tracing the lines accu- 
rately between effects and their preceding causes. 
APPLICATIONS. 
There are many operations of nature, otherwise inscrutable 
in their relations, which appear to be explained through this 
law of persistence of force. Under the consideration of effects 
through law, phenomena become linked with phenomena, 
observations become more exact, and the horizon of our inves- 
tigation becomes cleared. Let us see how far the theory we 
have herein developed will serve us in the consideration of 
those changes, which may be grouped in detail under the title 
of subordinate laws of inheritance. 
We will just call attention to what we have claimed in our 
context, that heredity is itself developed in strict conformity 
to the principles developed by this law. For the new force, The Philosophy of Breeding. 
39 
concrete in the offspring, is but at first a transference of 
forces possessed by the parent. To illustrate more fully : 
the piece clipped from a polype is but a portion of the polype 
formed by the same forces, and its development impressed by 
the same force which caused the development of the body 
from which it was derived. Therefore, in the absepce of 
counteracting influences, there must be resemblance between 
the two pieces, the parent and the new individual,—the off- 
shoot. The law of variation is also a development under this 
law; for causation, being universal, and the environment 
under constant change, it is inconceivable that two individuals 
should be exact counterparts of each other, no matter how 
near their kinship. Thus constant changes produce corre- 
sponding variations, and, so long as vitality exists, there is a 
constant effort on the part of living structure to maintain 
itself in equilibrium with the various forces affecting it, and 
we hence have the possibility of evolution. In the phrase, 
heredity with variation, we have an expression for conditions 
which are unmistakably directed and ruled by law. 
On a general law of vital periodicity.—Herbert Spencer, in 
his "First Principles,” devotes a chapter to the Rytlnn of 
Motion, in which he develops the fact that all changes appear 
to possess a periodicity of character, and that wherever there 
is a conflict of forces not in equilibrium, a rythm results; yet 
as motion is never absolutely rectilinear, rythm is necessarily 
incomplete. We find this same law exemplified in animals,— 
the vital functions all tending to run their course in fixed and 
recurrent periods, as illustrated by gestation and the phenom- 
ena accompanying it, certain processes of development, etc. 
In like manner, as the geysers of Iceland are intermittent,—; 
their spoutings ceasing, until, in process of time, sufficient 
forces are accumulated to overcome the resistance of the 
column of water which is expelled by the explosion,—so are 
oertain vital actions which require the expenditure of much 
power, and even as is a priori probable, all actions whatso- 
ever have a period of apparent quietude while they are accu- 
mulating the forces necessary for overcoming the antagonistic 
forces which they meet; for conflicts are continually occurring 
in nature, and a struggle exists, real, although often unnoticed, 
to maintain that constant equilibrium which is the objective 40 
The Law of Inheritance ; or, 
point of vitality. These rythmic actions, once formed, tend 
to be transmitted under the law of persistence of force, and 
the conditions involved fall under the laws grouped subor- 
dinate to inheritance. Hence a general periodicity, exhibiting 
itself as a law, and race, species, individual periodicity every- 
where, alike in principle, differing in detail. 
Characters common to many species of a genus are found to 
resist variation, or to reappear, if lost, more persistently than 
the characters which are confined to the separate species; * and 
the longer any character has been transmitted by a breed, the 
more firmly it will continue to be transmitted.f These two 
propositions are essentially similar, as dependent for their 
establishment on similar facts of observation. In general 
terms, antiquity of character adds strength. From the con- 
sideration of the laws involved, we see that each cause must 
produce a corresponding effect, and as each germ is a concrete 
force representing the sum of all the forces, whether plus or 
minus, acting on its past, it must be influenced during each 
generation by the continued presence of the same concrete 
force. The truth of this reasoning is illustrated by the facts 
of evolution, that generic characters are stronger than specific 
characters; that individual variability is general, and specific 
resemblance more constant; that crossing tends to produce 
variability, and breeding to pedigree to produce likeness. 
The apparent exceptions to this law of antiquity of character 
are numerous ; for whenever, from whatever cause, another 
force prevails for a season, this prepotency gained from anti- 
quity in natural course may disappear; but the fact that this 
disappearance is oftener in individuals than in species, and in 
species than genera, illustrates the correctness of our law. 
Now, the accumulation of forces in one direction, either 
through a " spontaneous ” ( ?) variation or through breeding, 
may, and often does, introduce a prepotency which will pre- 
vail over characters which have been assumed during many 
generations. This is illustrated by the Shorthorn cattle, a 
comparatively modern breed, which seems prepotent over the 
majority of the breeds with which they are crossed. The 
Ancon sheep, as well as the Mauchamp merinos, are illustra- 
* Darwin, An. and PL, under Domest., Vol. I., p. 139. 
t Darwin doubts, ip. cit., Vol. II., p. 82. The Philosophy of Breeding. 
41 
tions of ” accidental ”(?) variations, being prepotent over 
long-assumed characters ; but in these cases the results were 
partially aided by selection. 
Embryo more slightly modified than adult animal.—In the 
womb there is a striking resemblance between the products 
of very diverse animals at certain periods of their growth; 
and it is as growth advances that the differences become 
definite enough for immediate recognition. In the young 
animal, as in the foal or calf, the difference between animals 
of different breeds is at birth but slight compared to those 
which exist between the adult animals. In certain charac- 
ters, such as the sexual, we find development only occurring 
at a considerable interval from birth. This one instance of a 
process continually in action may be formulated in the law of 
development at corresponding periods of life. It is clear that 
these two expressions of facts, in constant occurrence, are 
somehow linked together,—the young animal being but a 
continuation of the embryonic life under changed environ- 
ment. When we consider that each animal is, in turn, the 
sum of his past, plus his present,—that is, the force which 
has originated, or which we recognize as vitality, has changes 
impressed on it during each period of its history, it will be 
perceived that the existing animal could not be exactly what 
it is if any change had taken place in its previous condition. 
Under the law of persistence of force, each concrete force is 
just what it is through the changes which have been impressed 
on its constituent units or parts. Any change of its unities, 
at any one period of existence, produces a corresponding 
change in the nature of the concrete force, whose expression 
is the specific or individual life. We therefore have periods 
of development; for, in the reproduction of an animal, the 
forces come at first entirely from the past, and are modified in 
turn by their entire past; and these inherited forces after- 
wards act against, as well as are modified by, environment. 
But to have a concrete force resembling another concrete 
force, there must be a similarity between the causes which 
have produced or developed. At each moment of the history 
of an animal, changes are being impressed, and the state of 
the animal at this moment has been determined by its previous 42 
The Law of Inheritance ; or, 
state. We thus have a continual series of changes going on 
under law, in which the past forces are continually in action, 
and a given result can only occur through predetermined 
forces in the past. Hence an order to development. Hence 
the element of time, during which changes may occur in suc- 
cession preparatory to the final result. Hence, in embry- 
ology and immature growth, a guide for the study of the 
history of past changes or evolution. 
Correlated variations, as of homologous parts, and correla- 
tions in general, can be understood under this view of forces, 
continuously modifying and influencing each other. When 
the phenomena of life first appeared, the struggle for exist- 
ence commenced, and in meeting the requisite equilibrium, 
changes became impressed in relation with the complexity of 
environmental forces, differentiations occurred, and the animal 
was gradually built up in its wondrous intricacy, yet har- 
mony ; each force concerned acting on, and being acted upon, 
by other forces concerned. Where we recognize this action 
of one force (considered concrete in its results) upon another 
(considered likewise), we define the action as correlation. 
Thus, in all the breeds of the pigeon, the length of the beak 
and the size of the feet are correlated. All modifications 
which occur influence subsequent developments, not only of 
the same parts, but also of all other parts with which it is 
intimately enough connected. In this we have correlated 
variations, in this but an expression of results following the 
doctrine of the indestructibility of force, which teaches that 
force, in common with matter, cannot be created, but can only 
be converted, and is subject to changes, but never to loss. 
In the correlations between bone and hair, we have different 
structures built up in part from the action of the same forces, 
as is shown by the history of their development. We there- 
fore have a certain affinity between them, and a change 
impressed on one is apt to be followed by corresponding 
changes in the other. Were we sufficiently acquainted with 
the forces which go towards making up the animal, the 
numerous immediate forces could be referred to successive 
intermediate forces, into which they could be grouped, until 
finally the simple force would be reached,—a conception The Philosophy of Breedmg. 
43 
expressed by vitality in the abstract. Correlation is, conse- 
quently, but another expression of persistence of force. It 
is a recognition of the mutual dependence of all structures 
upon simple, harmonious law. 
Prepotency.—As all causes are followed by effects, we must 
believe that forces which have long acted, or have been accu- 
mulated in one direction, have done so to the exclusion of 
other forces which might have acted in their place, and hence 
must be supposed to have had a stronger influence than if 
they had acted through a less period of time, for continued 
effects must have followed their continued presence in an 
unstable equilibrium, like vitality. Hence, the term pre- 
potency expresses the fact that a force, through long continu- 
ance or otherwise, has, through its own strength, acquired a 
preponderating influence over other forces. We thus have 
prepotency of breed,—as illustrated by the case given by 
Godine, where a ram of a goat-like breed, from the Cape of 
Good Hope, produced offspring hardly distinguishable from 
himself when crossed with ewes of twelve other breeds; 
prepotency of sex,—as illustrated by the Shorthorn bull 
" Favorite,” referred to so often in Shorthorn pedigrees. 
When, from any cause whatsoever, a force acts in a manner 
stronger than another force, it is prepotent. If forces have 
been accumulated through selection, or through breeding in 
any one direction, we have a prepotency of such forces over 
other forces which are unable to resist,—each force standing 
on its own strength, however it may have been accumulated. 
Pedigree, or the breeding in line, has a tendency to strengthen 
the points of value ; so also has purity of race ; so also has 
selection ; so also has the accumulative action of changed 
conditions of life. Prepotency is, therefore, but a term 
expressive of a fact, that of a number of forces found amid 
many diverse conditions,—as in the maintenance of an equilib- 
rium with changing conditions,—some are stronger than 
others. If we consider force as persistent, and bear in mind 
the law of causation, the predominance of some forces over 
others becomes a necessity ; and the continuation of a force 
through a long time, that is, antiquity ; or the accumulation 
of forces in one direction, as by breeding to pedigree ; or any 44 
The Law of Inheritance ; or, 
other method through which we obtain causes acting contin- 
uously in one direction, strengthens such forces, and produces 
in those cases where the action is recognized, the phenomena 
called prepotency. 
On the relations betiveen the period of development of a 
character and its transference to one sex or to both sexes; or, 
as again more fully expressed by Darwin, variations which 
first appear in either sex at a late period of life tend to be 
developed in the same sex alone; while variations which first 
appear early in life in either sex tend to be developed in both 
sexes. As sexual characters receive their development late 
in life, through the doctrine we are here enunciating there 
must be, necessarily, a correlation between the sexual distinc- 
tions and those parts developed under process of law at the 
period of their activity. Hence, a prepotency through sex 
might be established. In early life, the sexual organs being 
immature, there is less of correlation with sex, and, conse- 
quently, less sexual prepotency. When, therefore, the adult 
male differs from the adult female, and from the young of 
both sexes, we may assume that the variations which brought 
it about occurred late in life; for, through the transmissal of 
forces, the adult is the product of forces acting through the 
young, and the history of the development must furnish a clue 
to the order in which the changes have occurred. When the. 
adult male closely resembles the adult female and the young 
of both sexes, the variations through which their characters 
were acquired occurred in early life.* 
Inheritance limited by sex.—In correlation of structure, 
brought about through persistence of force, we seek an 
explanation for this curious phenomenon. It is seldom that 
this species of inheritance is absolute; but this can be 
explained from the fact that, in foetal life, the distinctions 
between the sexes are less than in adult life, and therefore 
their influence is less strongly marked upon correlations. It 
must be borne in mind that the individual is the product and 
the equilibrium of all the forces which have had to do in his 
making, both past and present. Originally, a simple force, 
becoming differentiated, changes character, and concrete 
* Darwin, “ Descent of Man,” Vol. I., p. 277. The Philosophy of Breeding. 
45 
forms result, the direct effect of the changes which are affect- 
ing and have acted. The sexual changes are of importance ; 
produced by environmental circumstances, they in turn, as 
concrete forces, must influence the whole structure. This 
they do, beyond denial, and sexual distinctions must espe- 
cially influence, to some extent in early life, to a great extent 
in adult life. 
Inbreeding—Crossing.—Close inbreeding has a tendency 
to induce sterility, while crossing is universally regarded by 
breeders as bringing vigor. Darwin regards it as an estab- 
lished law of nature, that all organic beings profit from an 
occasional cross with individuals not closely related to them 
in blood ; and that, on the other hand, long-continued close 
interbreeding is injurious. It is the belief of physiologists 
that every act of development tends to diminish the germinal 
capacity, while every act of generation tends to renew it; and 
it is even probable that in plants even self-fertilization seldom 
occurs, but the stigma receives pollen from other flowers than 
its own through * contrivances often of the most wonderful 
complexity. ' This is a form of expression for the fact that 
every change is brought about through the utilization of a 
force, and that the forces may gradually become weakened in 
producing changes unless a power of regeneration be given 
them by a union with fresh forces. In inbreeding we are 
dealing with forces of a similar character,—that is, they 
approximate to a nearer likeness than do the forces the 
product of an out-cross, on account of having a greater 
similarity of history in their past. We consequently have an 
approach towards the development of new individuals without 
the intervening act of generation,—as, by fission, gemma- 
tion, etc.; that is, an approach towards a developmental 
process, as distinguished from the generative process, and, 
consequently, a tendency to shorter duration to the life,—this 
means weakness, lessened constitution, etc., etc. In an out- 
cross, on the other hand, wo have an entire departure from the 
developmental idea towards the generative, and a consequent 
vigor, or renewal of force. If the out-cross be, however, too 
violent, a hybrid may be the result,—that is, the forces neces- 
sary for fertility are absent, either on account of too great 46 
The Law of Inheritance ; or, 
antagonism between the forces present in either parent, or 
because they are not of such a nature as to combine. In 
hybrids, therefore, we have usually sterility, but also the 
possibility of producing offspring,—as, indeed, is occasionally 
the case,—the result depending upon the structure and com- 
position of the forces which severally are engaged. In mon- 
grels we find great variability and little prepotency, as a rule, 
all resulting from the doctrine of persistence of force. 
The other effects of inbreeding—as the transmission of 
defects in an accumulated form—fall directly under the fact 
of inheritance, and need not be considered in this place. 
The unequal fertility between reciprocal crosses connects 
the consideration of mongrels and hybrids, and seeks explana- 
tion from the same laws. 
In crossing animals of the same race we have a union of 
forces under the laws of breeding, but on account of our little 
knowledge concerning the relative strength and the combined 
action of the forces we are using, the results are apt to be 
very variable. When two forces meet in antagonism, each 
is modified and changed according to the law of mechanics, 
but neither force is obliterated ; the effect of the struggle 
remains, while the forces may be in abeyance. Like the 
circular ripple of the pebble dropped in the water of smooth 
surface, the effect is ever acting, ever extending, and we thus 
have a series of actions modifying changes for all time. 
Characters in an animal are never obliterated, but may dis- 
appear from our view. We have, in crossing, a means for 
the modification of race, by producing changes through direct 
antagonism of force. We also have in free crossing a means 
for the preservation of uniformity between members of the 
same race. Like a two-edged sword, the law of crossing cuts 
both ways, according as its principles are applied, and under 
the government constantly of the great law of nature,—that 
of the persistence of force. As the antagonism of forces may 
be considered in the light of a mutual absorption, other forces, 
too weak to otherwise appear in a form recognizable to us, 
may appear. Hence, we say, that crossing produces a ten- 
dency to reversion or atavism. 
Selection.—This is simply an expression of a means to an The Philosophy of Breeding. 
47 
end. It signifies the accumulation of a force in a chosen 
direction. As used by the breeder, selection means modify- 
ing the laws of animal nature through human knowledge and 
skill, so as to predetermine the result. If unconscious, it is 
the accumulation of prepotency through law, not under the 
voluntary direction of man. The very terms used in discussing 
the doctrine of selection, presuppose the doctrine that force is 
persistent and is subject to the law of matter. 
Malformations.—These are all subject to law, which is not 
only a priori reasonable, but which has been already partially 
formulated and discussed. These, whether monstrosities or 
the opposite, can derive an explanation from the consideration 
of the doctrine of forces. In the case of dwarfs, develop- 
mental force is present, growth force seems defective. In 
monsters, we may have a deficiency of certain forces at a 
determined point, as in cases of arrest of development, or an 
accumulation of forces in a direction injurious to the individ- 
ual. Nature only attains perfection (equilibrium) through 
repeated elforts, and those not fitted to exist perish in the 
struggle of life. 
Imagination.—That there is an influence between the womb- 
contents and the mother, is illustrated in many ways. In the 
woman, the development of new ova is checked upon the 
occurrence of impregnation, and lactation also appears, in 
the majority of cases, to have the same effect. Diseases of 
these parts are apt to produce mental disturbance, and in 
other ways a close connection is shown between the mental 
and reproductive functions. Causes, therefore, acting on one 
must necessarily affect the other ; and, through persistence of 
force, the child must also be influenced in turn, for it receives 
its supply of force through the mother. The physical con- 
nection of mother and offspring is not, however, direct, and 
the influence of one on the other is not as well marked as if it 
were otherwise; yet the influence on each other must be 
reciprocal. An impression of long duration would seem to 
have a power greater than one of short duration, or even, 
possibly, than a violent impression of short continuance. 
Effects of a previous impregnation.—By the law of causa- 
tion, there must be a mutual relation between mother and 48 
The Law of Inheritance. 
offspring in the womb. We recognize this fact in practice, 
and in reasoning it naturally follows from persistence of 
force. The force received from or through the father, uniting 
with the force presented by the female, coalesces, and during 
growth and development must influence, in some way, the 
female structure,—for causes and effects are correlative; and 
we have in the young, modifications, through developments and 
growths, going on continuously, supported from the mother; 
and it is unthinkable that there is not an effect being pro- 
duced, in turn, on the mother from these operations.