S Reprint : 
THE KANSAS CITY MEDICAL RECORD 
5"he Ihrthohjgical 
Signification of 3mmnnitii. 
A. L. CHAPMAN, A.M., M.D., 
KANSAS CITY, MO. Press of 
HUDSON-KIMBKRLY PUBLISHING COMPANY 
Kansas City, Mo. Reprint: THE KANSAS CITY MEDICAL RECORD, November, 1893. 
The Pathological Signification of Immunity. 
By A. L. CHAPMAN, A.M., M.D., 
KANSAS CITY, MO. 
Read before the Kansas City District Medical Society, September 7, 1893. 
How it is that the human organism is not 
liable to he invaded by certain infections and 
contagious diseases more than once in the life- 
time, has occupied the best thought of the 
medical profession from the earliest of times, 
and during the last two decades more earnest 
efforts have been made for the solution of this 
question than ever before; nevertheless, the 
pathological, or, if you please, the physiolog- 
ical, signification of immunity has not yet been 
satisfactorily given. Now here in the begin- 
ning of this paper I desire to emphasize the 
fact, that from all the most recent investiga- 
tions upon this subject which have been 
accessible to me, it is my conviction that the 
facts given us in the various processes of fer- 
mentation afford data which are competent to 
explain how this immunity from the reinva- 
sion of the organism by contagious diseases 
may be acquired by man and by animals. 
What then is fermentation, and how is it 
accomplished ? Fermentation is a certain defi- 
nite modification which takes place in the 
chemical constitution of an organic body, and 
this modification is accomplished by virtue of 
a chemical, unorganized and lifeless ferment, 
which is secreted by a living cell. Fermenta- 
tions, according to views which now universally 
obtain, are divided into true and false fermenta- 
tions; the former are alleged to depend upon the 
action of living cells, and hence are called 
organized or living ferments; the latter are 
made to depend upon unorganized and lifeless 
substances which these living cells themselves 
secrete, and are therefore called lifeless or 
chemical ferments. The transformation of 
glucose into alcohol and carbonic acid by the 
so-called yeast cell is an example of the first; 
the transformation of albumen into albuminose 
by the action of pepsin is an example of the 
second. Now I purpose here to take a some- 
what different view of the matter and to 
advance the proposition, namely, that all fer- 
mentations are, at bottom, fundamentally one, 
and that the primary and efficient impulse 
to these fermentations is impressed, not by an 
organized or vital ferment, but by a ferment 
which is chemical, unorganized and lifeless. 
In venturing to make the broad statement 
that fermentations, that all fermentations are 4 
THE PATHOLOGICAL SIGNIFICATION OF IMMUNITY—CHAPMAN. 
due and referable to chemical and not to vital 
causes, I confess that I have done so with some 
reluctance, especially as it is in contradiction 
to the views advanced by such men as Pasteur, 
Chauveau, Koch, and others whose splendid 
achievements in these very fields have shed 
unfading glory on the medical name; yet stand- 
ing, as I feel myself, behind facts which are 
incontestable in the support of this view, I 
will neither hesitate nor waver in defending 
the position here taken. Let us then take a 
succinct and cursory review of some of these 
fermentations, or transformations, as we know 
them to occur in both animal and vegetable 
bodies. 
Pepsin, for example, which is an unorgan- 
ized, lifeless ferment, secreted by the peptic 
cells of the glandular follicles of the stomach, 
is, “by virtue of its presence,” endowed with 
the capacity of essentially altering the chem- 
ical relations and physical qualities of the 
albuminous substances received by the stom- 
ach, and of rendering them diffusible and 
absorbable in the organism. 
The living peptic cells of the stomach are 
in no way concerned in this transformation, 
but it is something which these living cells 
secrete—a pepsin, a ferment at once and for- 
ever chemical and unorganized. 
The very same thing can be said, and for 
the very same reason, of all the chemical 
transformations going on in the organism. It 
it by a chemical ferment, and nothing more 
than a chemical ferment, secreted by living 
cells, by which starch is transformed into glu- 
cose, fats saponified, albumens converted into 
peptones by the pancreas, and sugar into gly- 
cogen by the liver. The specific functions of 
these ferments do not depend, in any way, 
upon their relations or proximity to the living 
cells which produced them, but are abundantly 
able to perform the same offices, as well with- 
out as within the organism. Let us now 
hastily glance at a few of the most common 
fermentations as they are known to take place 
outside of the body, and, in order that I may 
not weary you by submitting a detailed para- 
digm of a number of fermentations which are 
closely allied, as the alcoholic, the acetic, the 
lactic, the butyric, etc., I shall here, for the 
purpose of economizing space and time, briefly 
consider this whole class of fermentations, the 
so-called true fermentations, under one view, 
as all of them are held, and I may say univers- 
ally held, to be set up and carried on by the 
vital action of micro-organisms. Take, for 
example, the alcoholic fermentation of glucose. 
This fermentation has long been held as a 
notable and convincing illustration of the 
action of a ferment which is organized, a 
living micro-organism, the saccharomyccs cer- 
evisia, the so-called yeast cell. Let it here 
be particularly noted that glucose, or grape 
sugar, exists by nature in the expressed juice 
of the grape, and that it exists by nature no- 
where else. For the purposes of nutrition all 
other forms of sugar, as well as starch and its 
derivatives, must be converted into grape 
sugar, for no other is assimilable by the tissues. 
Now it is everywhere conceded that in all 
these transformations of starch into sugar, 
and of one form of sugar into another form, 
and of any or all of these forms into glucose, 
nothing but a chemical ferment is required. 
It is certain that no vital ferment, that the 
vital action of no micro-organism,is required or 
in any way concerned in these transformations. 
Barthalot has shown, and he was the first to 
show, that the conversion of cane sugar into 
grape sugar by yeast is not done, as it was at 
one time supposedly the living yeast cell,“ but 
by a chemical ferment which can be abstracted 
from the yeast and will still act in its absence.” 
“In fact,” says Barthalot, “yeast itself cannot 
utilize cane sugar, but must first get it 
changed into grape sugar by this soluble fer- 
ment, so that the conversion of cane sugar 
into alcohol is a double event, and requires HIE PATHOLOGICAL SIGNIFICATION OF IMMUNITY—CHAPMAN. 
5 
first the action of a lifeless ferment to turn 
the cane sugar into the more hydrated grape 
sugar, and second, a living ferment, yeast, to 
turn grape sugar into alcohol.” Barthalot 
says further: “If yeast can secrete, as it 
does, a soluble, lifeless substance which in- 
verts sugar, may it not be that it repeats the 
process substantially in changing grape sugar 
into alcohol?” In corroboration of this, it 
may here be stated that wherever yeast cells 
are found existing together, as at the bottom 
of vessels where the fermentation of glucose 
has ceased, there is also to be found an albu- 
minoid, intercellular substance, secreted by 
these cells, a true chemical ferment, and capa- 
ble of setting up the vinous fermentation. 
Furthermore, it is known that the alcoholic 
fermentation will not take place in a /wrc solu- 
tion of glucose, that is, in a solution not con- 
taining the albuminoid matter, the chemical 
ferment native to the grape itself, however 
favorable the temperature, and however ex- 
posed to the air; but if a little of the nitrogen- 
ous, albuminoid matter—chemical ferment — 
which exists by nature in the expressed juice 
of the grape be added to the solution, fermen- 
tation shortly begins, and is carried on to com- 
pletion. 
Parenthetically I must here say, according 
to the authority of all chemists and chemistries, 
that, whatever may be the part which micro- 
organisms may play in the fermentation proc- 
esses, the alcoholic fermentation of glucose 
would not be possible without the presence of 
the vegetable albumen which exists by nature 
in the grape, so that it is now a chemical aph- 
orism : No albuminoid {body) ferment, no fermen- 
tation. In the process of brewing also,and in the 
preparation of spirits from grain, we again meet 
with this ever-present albuminoid ferment, 
the yeast, without which, as has already been 
shown, no alcoholic fermentation is possible. 
Here in the grain we find this albuminoid fer- 
ment in the form of diastase deposited by ! 
nature in the grain itself, just as we have pre- 
viously found the so-called yeast ferment to 
exist by nature in the grape under the form of 
vegetable albumen, which,by the absorption of 
oxygen from the air, enters into decomposition 
and becomes the one necessary and universal 
ferment in all vinous fermentations. Again, 
in the ammoniacal fermentation of urine, 
which has all along been attributed to a micro- 
organism, the micrococcus urea, M. Masculus 
has shown that we can obtain from altered 
urine, by the action of alcohol, a precipitate, 
a chemical ferment, which is able to transform 
urea into carbonate of ammonia. Thus it ap- 
pears that, as in the alcoholic fermentation of 
glucose, and as in the fermentation of g'ain in 
the manufacture of beer and of spirits, so also 
in the fermentation of urine the fermenting 
agent is found to be, not the action of a living 
micro-organism, but the chemical action of a 
lifeless, unorganized ferment. In one word, 
the conversion of sugar into alcohol and car- 
bonic acid, upon the authority of Fown's late 
edition of chemistry, "never takes place except 
in the presence of sonic nitrogenous body of the 
albuminoid class in a state of decomposition." 
Now because bacteria are often,perhaps always, 
present during what are called the true fer- 
mentations, that is, in those fermentations 
which occur exterior to the organism and which 
are concerned in the regressive or destructive 
metamorphosis of organic bodies, we must not 
conclude therefrom that these bacteria are, at 
least by their vital actions, the cause of these 
fermentations, and for two reasons: ist. Bac- 
teria are themselves nitrogenous bodies of the 
albuminoid class, and when they perish, as 
they are constantly doing, they at once become 
the one definite and specific chemical ferment, 
as defined by Fown—"nitrogenous bodies of the 
albuminoid class in a state of decomposition. 2d. 
These bacteria are themselves able to secrete 
a lifeless chemical ferment which can set in 
motion the fermentative process. From these 6 
THE PATHOLOGICAL SIGNIFICATION OF IMMUNITY-CHAPMAN. 
considerations three facts obtrusively present 
themselves to us: First, bacteria cannot set 
up fermentation in bodies consisting exclu- 
sively of amylaceous or saccharine matter, 
because, requiring nitrogen as a necessary part 
of their nourishment, they cannot maintain 
their vitality upon these non-nitrogenous 
bodies alone; the second, that these ferment- 
ing albuminoid matters, affording all the food 
elements necessary for their nutrition, would 
be a sufficient reason to account for the move- 
ment of bacteria thitherward in quest of food; 
and the third, that the selfsame albuminoid 
matters enter into fermentation in all the so- 
called false fermentations by the action of a 
purely chemical ferment alone, and where no 
bacteria are known to exist. If, therefore, 
these micro-organisms must be held as stand- 
ing in any causal relation to these fermenta- 
tions, they must do so either by secreting a 
chemical ferment, or by surrendering their 
defunct albuminoid bodies as a “yeast” for 
these fermentations. 
Now I desire here to signalize the state- 
ment, namely: that we violate no law of bac- 
teriology, that we violate no law of biology, in 
allowing the bacteria the power of secreting 
a digestive ferment, a ferment that shall be 
able to perform for them the same physiolog- 
ical functions which this ferment is known to 
perform in all other living beings, namely: 
the chemical transformation and digestion of 
the food elements destined for their nutrition. 
And if we do not desire to advance the doc- 
trine that these bacteria occupy an unique and 
isolated position which is not assumed by any 
other living beings upon the globe, then we 
must allow that these organisms are endowed 
by nature to secrete a ferment, and that that 
ferment shall be able to digest for them their 
food, rendering it absorbable and assimilable 
by their tissues, as all other living beings are 
qualified to do. No, there must be no differ- 
erence; the fundamental laws of biology, the 
universal laws of nature, are over all alike — 
and just as man would inevitably perish though 
his digestive cavities were filled with the most 
nutritious food-stuffs, did not those chemical 
ferments which Nature has placed within his 
organism work a chemical transformation upon 
that food, thus rendering it absorbable and as- 
similable by the organism; so, too, would the 
bacteria succumb to dissolution were they not 
also able to chemically transform by their own 
ferments the materials upon which they must 
live. No living being, neither vegetable, bac- 
terian, nor animal, is able to appropriate to its 
own nutrition the food material in the form, 
in the chemical and physical form, in which 
that food is found to exist in nature; but, on 
the contrary, each must be qualified by nature 
to transform this material suitable to the phys- 
iological requirements of the organism. Now, 
is there any other power or instrumentality 
possessed by any being amongst all the living 
which is able to do this but a ferment, a fer- 
ment chemical and lifeless? Emphatically there 
is no other. Then it becomes to us a matter 
of necessity, we are, nolens volens, constrained to 
accept the proposition, namely: that wherever 
a bacterion is found to exist and to nourish 
itself, it must there be found to do this by set- 
ting up a fermentation in the organic body or 
tissue wheresoever it is found. 
One word now on putrefactive fermenta- 
tions. The putrefactive fermentation of albu- 
minous matters, of both animal and vegetable 
origin, is accomplished by a great variety of 
micro organisms. For each step in the down- 
ward march of these organic matters a defi- 
nite and specific micro-organism is required, 
and their total destruction can only be accom- 
plished and be complete after myriads of these 
organisms have been employed. The chem- 
ical products resulting from these decompo- 
sitions are so numerous, varied and complex 
that they have never yet been definitely made 
out. Among these products are to be found THE PAIHOLOGICAL SIGNIFICATION OF IMMUNITY—CHAPMAN. 
7 
a great many poisonous substances, patholog 
ical irritants, of which recent pathological 
writers have said so much. Now since we 
have learned that bacteria have no other way 
of obtaining their nourishment but by decom- 
posing organic bodies, and that they can only 
do this by the dissolving power of that ferment 
with which Nature has beneficently endowed 
them, the conclusion is imposed upon us, it 
comes to us by the authority of a voice from 
heaven, that the molecular edifice of defunct 
albuminoid bodies, that the organic tension by 
which these bodies are held in unbroken unity, 
must be loosened and broken up in these putre- 
factive fermentations in precisely the same 
way, and by precisely the same instrumentality 
by which we have already found this to have 
been done in the fermentation of glucose, and 
in the peptic fermentations of albumen in the 
human stomach; and it may be stated here as 
a fact, a little remarkable, but no less remark- 
able than true, that, upon the authority of 
Fliigge, the very first product that appears in 
these putrefactive fermentations is a peptone 
in every respect similar to the peptone formed 
by the human stomach. If, then, the putrefac- 
tive process begins, as it does, by a chemical 
ferment secreted by bacteria, is it not reason- 
able to conclude, nay, is it not certain, that all 
other bacteria, in carrying on and completing 
this process, would do their work by exactly 
the same means? It is true that beings so 
microscopically small must be only able to 
secrete a ferment exceedingly minute, often 
too minute for chemical isolation, but it has 
long ago been known that a little leaven may 
leaven the whole lump, and that the veriest 
spark may cover a great city. 
lint, Mr. President, it ought to have been 
enough to have simply stated, in the beginning 
of this paper, that Nature sometimes employed 
a chemical agent in the fermentation of organ- 
ic bodies, and then to have sat down. It 
ought to have been enough to have plighted 
our undying faith in the veracity of Nature, 
and in her'immutable and unchangeable laws; 
that yesterday and to-day, from the beginning 
till now, she has worked according to one 
universal law, always doing the same thing in 
the same way. It would be monstrous to sup- 
pose that Nature would employ two diamet- 
rically opposing agencies to accomplish one 
and the same specific process; that the living 
and the dead should be made able to perform 
the same functions; that now a living, now 
a lifeless ferment should be employed to ac- 
complish a certain definite and specific fermen- 
tation in organic bodies. No, Nature does 
not abort. Here there is neither variableness 
nor shadow of change. In all the long 
cycles of past times her creative and trans- 
formative processes have been the same, and 
the agencies by which these processes began to 
appear and to continue on in their forward 
movements are just the same now as in the 
beginning. Away back in the beginning ot 
the ages, before any organic form was born, 
before life had appeared upon the globe, 
before any organism had been fitted up for 
the reception of a new and most august 
being, soon to make his advent into the world, 
a being endowed with sensation, sympathy, 
and thought, conscious of his own existence, 
and capable of explaining it -before these ap- 
peared upon the globe it became necessary, in 
the economies of Nature, that a new body 
should be formed—a body having no proto- 
type or kinship in the then existing nature 
—a body at once creative and transformative, 
capable of breaking the bonds which had held 
for myriads of ages the inorganic wojdd in 
utter lifelessness—and a body capable of intro- 
ducing a new and a totally distinct order of 
being. This was chlorophylle. But what 
is chlorophylle? It is a ferment; a fer- 
ment chemical, unorganized and lifeless, 
identical in its chemical composition and 
in its physiological functions to the fer- 8 
THE PATHOLOGICAL SIGNIFICATION OF IMMUNITY—CHAPMAN. 
ments we have been here considering. 
Sir, these most phenomenal and extraordi- 
nary bodies, of which clilorophylle is the pro- 
totype, have never yet been explained. To 
the physiologist and to the chemist of this day 
they are confessedly inexplicable and unknown; 
hence they are still refered to under the enig- 
matical and shadowy appellations of “catalytic 
bodies,” of bodies “acting by their mere pres- 
ence.” Although having no life within them- 
selves, they constitute the one sole necessary 
and indispensable medium by which life began 
to appear in the vegetable, and by which it 
now continues to persist in the animal world. 
Remove from the earth its mantle of immortal 
green which clilorophylle imparts, take away 
from the vegetable cell this lifeless ferment, 
and very soon would vegetable life, very soon 
would all life, disappear from the earth. The 
inorganic elements would then cease to arrange 
themselves into organic forms, and these ele- 
ments would again become forever fixed and 
immovably bound down in the inorganic 
world as they were in the beginning. 
Having thus briefly and rapidly touched 
upon some of the most common and best 
known fermentations, and having ascertained 
their cause, we shall now endeavor to show 
that the pathological signification of immunity 
is implicitly given in the modifications which 
occur in the chemical constitution and physi- 
cal qualities of organic bodies during the proc- 
ess of fermentation. And here I desire to say, 
and I desire to say it in earnest emphasis, that 
the pathological signification of immunity is 
not soluble upon the vital theory of fermen- 
tation, and that it will not admit of solution 
if this theory be true. Hence the most astute 
men of the profession, who, if I am not mistaken, 
implicitly subscribe to this vital theory, have 
yet been unable to give any satisfactory solu- 
tion of this question. But upon the chemical 
theory of fermentation the signification of im- 
munity, I must be allowed to say, becomes 
natural and easy. Now as a basis to the solu- 
tion of this question I will here state, what I 
take to be, a self-evident proposition, namely: 
When the chemical relations and the physical 
qualities of an orga)iic body have been modified 
by the action of any ferment, the body thus mod- 
ified xvill not admit of any additional or further 
modification by the same ferment, so long as that 
modification exists. It will be admitted here 
as also self-evident that any body undergoing 
fermentation must, ipso facto, undergo at the 
same time a certain definite modification in its 
chemical nature. 
Now, is it not conceded by the medical 
profession that infectious and contagious dis- 
eases are induced by the presence and action 
of certain pathogenic organisms received with- 
in the system? Yes. Is it not also conceded 
that these pathogenic organisms, in producing 
these diseases, act simply in the capacity of 
ferments, that is, by altering the chemical 
relations and physical qualities of the tissues? 
Yes. Is it not admitted, furthermore, that 
these altered tissues are immune against the 
bacteria which produced them, and that it 
would require totally distinct bacteria to re- 
ferment these altered tissues? Yes. But 
when we say that such altered tissues of the 
organism are immune against the bacteria 
which formed them, do we not implicitly say 
that the organism itself is immune against a 
disease of which those bacteria are the cause? 
Yes. Well, then, is not this immunity? Yes. 
And when we say that no pathogenic bacteria 
can referment the product of its own fermen- 
tation, is not this the pathological reason of 
immunity? It is. I will stand to it before the 
world that the pathological signification of 
immunity has now been given. 
To account for immunity against a second 
invasion of the system to infectious and con- 
tagious diseases many theories have been ad- 
vanced. The “exhaustion theory,” proposed by 
Pasteur, sets forth that pathogenic bacteria t llli PATHOLOGICAL SIGNIFICATION OF IMMUNITY-CHAPMAN 
9 
take up certain elements of the organism for 
their own nutrition, and when these elements 
have been exhausted, there remaining no other 
elements in the organism suitable for their 
nourishment, the body, by necessity, becomes 
immune. Then there is the theory proposed by 
Chauveau, called the “retention theory,” which 
sets forth the notion that certain pathological 
micro-organisms form special products which 
are retained by the system, and which are in- 
imical to the growth and development of the 
organisms which form them; so that a second 
invasion by the same organism cannot occur. 
Now if, on the theory of Pasteur, something 
must be removed from the organism every 
time it was invaded by an infectious disease, 
in order that immunity shall be acquired, the 
body after repeated infections might be sub- 
jected to a loss of material incompatible with 
its physiological functions, and hence this 
theory must be held as inadmissible. On the 
other hand, if something must be added to 
the organism inimical to the microbe which 
would infect it, the organism, after many of 
these infections, must become loaded up with 
a goodly quantity of foreign material; and all 
this for the sake of immunity, now from this, 
and now from that infectious disease. Then, 
also, there is the “tolerant theory,” proposed 
by Sternsbergh, and then the theory of phago- 
cytosis, whose most distinguished advocate 
to-day is Klias MetschnikofF, of the Pasteur In- 
stitute, neither of which theories I can here 
particularly notice; not only for want of space, 
but also for want of ability to discover their 
force or pertinency—the former going upon 
the supposition that one may become so "tol- 
erant,” so accustomed to disease germs, that by 
and by they cannot hurt him; the latter that 
the leucocytes of the organism, like so many 
hungry terriers, guided on by an inscrutable 
“ cheoieotaxis," keep chasing after these bac- 
teria and devouring them It must not be 
forgotten, also, that millions, even billions, of 
these germs arc able to be produced in the* 
organism during a single day, so that the said 
leucocytes might be kept uncomfortably busy 
in keeping down the increase. 
Now the theory which I have ventured 
here to propose does not take anything away 
from the organism, it does not add anything 
to it, but it simply imposes a change of tissue, 
as a guarantee for immunity—a change of tis- 
sue produced by a cause known to exist in the 
organism, a cause competent to make a change 
of tissue and a cause operating according to 
the principles of a known and well-established 
law. This theory gives you a ferment as a 
cause of this change of tissue; it points you 
to a pathogenic bacterion which forms this 
ferment, and it assures you, according to the 
known laws of fermentation, that this tissue, 
that the organism itself, is not again assailable 
by the same pathogenic germ. Nor does this 
theory require you to accept any new, hypo- 
thetical or extraordinary law for its explana- 
tion, any strange or anomalous process in 
nature, as a ground and reason for immunity, 
but it points you to a physiological prototype 
creating immunity in the same way and by 
identically the same cause; it points you to 
the fermentation of albumen by a chemical 
ferment secreted by the peptic cells of the 
stomach, to the transformation of albumen to 
peptone by the action of this ferment, and it 
gives you a physiological guarantee that this 
peptone is immune against the action of that 
peptic ferment, and that this immunity will 
exist just as long as albumen shall maintain its 
changed physiological condition under the 
form of a peptone. It would be superfluous 
here to argue that the same must be true of 
the products of all other fermentations; for 
this would compromise the invariability of 
Nature; it would tend to hazard the maxim 
that “the part of a part is part of the whole.” 
If starch is transformed into glucose by the 
ptyalin of the saliva or by the amylopsin of 10 
THE PATHOLOGICAL SIGNIFICATION OF IMMUNITY—CHATMAN 
the pancreas, then, by this invariable law, 
glucose must be immune against these fer- 
ments. If the tissues have been transformed 
by the ferment action of the small-pox bacil- 
lus, then these tissues must be immune against 
the further action of that bacillus. If carbonic 
acid plus water have been transformed into 
starch by the action of chlorophylle, then must 
starch also be immune against this ferment. 
But then chlorophylle cannot act by its 
own unaided power—“of itself it can do noth- 
ing. Although the one sole necessary me- 
dium by which life and organic forms be- 
came possible upon the globe, it is not self- 
mediated ; it is mediated by light; it is quick- 
ened and put in motion by the solar rays, 
which work in it, with it and by it in all the 
vital operations. It has been eloquently shown 
by the immortal Draper that “vegetable growth 
and development is directly as the quantity of 
light; that for the decomposition of a given 
weight of carbonic acid and the formation of a 
given weight of gum a fixed and invariable 
quantity of light is required; that light really 
and formally enters into the organic structure 
and becomes one with it.” So that the light 
of the sun is the veritable life of the world. It 
is now our life; we are indeed the children of 
the sun, and are begotten by his rays. So 
that without any metaphor, without the least 
imagery of language, we can literally and truly 
look up upon the face of that great luminary 
and say unto him, in awe and filial adoration, 
“Our Father who art in heaven.” 
But in returning from this digression I 
cannot better conclude this paper, nor more 
effectively reinforce what has heretofore been 
said, than by reaffirming the maxim first form- 
ulated by Rudolph Virchow, namely, “That 
every pathological product must have a phys- 
iological prototype.” By this maxim we are 
then entitled to look for pathological immunity 
just where we have previously found physio- 
logical immunity, and if physiological immu- 
nity is given in a product formed by a physio- 
logical ferment, then we must expect to find 
pathological immunities in the products given 
to us in the pathological fermentations; but 
every physiological immunity is given in a 
product formed by a physiological ferment— 
therefore every pathological immunity is given 
by a law which ca?inot be broken, in a product 
formed by a pathogenic or pathological fer- 
ment. 
By way of parenthesis, I may here say that 
the two classes of fermentations heretofore 
referred to, the true and the false fermenta- 
tions, are each of them physiological actions 
and are at bottom fundamentally one—the so- 
called false fermentations being progressive 
and constructive; the true, regressive and 
destructive; but both are operated according to 
the same fundamental law. 
From' the foregoing considerations also it 
can be seen why it is that there is a fixed and 
natural limit to the periods of fermentation, 
just as there is to the periods of disease; why 
the alcoholic fermentation will cease when the 
fermenting liquid contains about 17 per cent 
of alcohol; why the ammoniacal fermentation 
will cease at about 13 per cent of carbonate 
of ammonia ; why the lactic fermentation will 
cease at about 1 per cent of lactic acid, and so 
of the rest. This is not because, as was once 
supposed, that the bacteria producing these 
fermentations perish, for they are seen to exist 
long after fermentation has ceased ; but it is 
because the products of these fermentations 
are inimical to the chemical action of the fer- 
menting bacteria, and can only continue in the 
presence of a limited per cent of their products. 
In putrefactive fermentation, in the fermenta- 
tion of albuminoid bodies,the inhibiting power, 
the anti-fermentation power of these ferment 
products, is exceedingly increased, so that the 
smallest quantity is able to protect against 
fermentation on the one hand, and to protect 
against disease on the other. This is exem- THE PATHOLOGICAL SIGNIFICATION OF I MM CATTY— CHAPMAN. 
11 
plified by the principle involved in vaccina- 
tion, where a particle microscopically small of 
these (albuminoid) pathogenic bacteria “in a 
state of decomposition" is able to protect the 
organism against the most active contagion; 
where the tiniest portion of blood serum of a 
person made immune, where even the milk of 
an immune mother, is able to protect against 
disease. If anything further was required to 
support the doctrine which this paper pro- 
poses, it is given in the fact, now universally 
admitted, that contagious and infectious dis- 
eases can be communicated to a healthy person 
by the defunct bodies of these bacteria “when in 
a state of decomposition." Therefore conta- 
gious and infectious diseases, all of them, are 
communicated to men and animals solely by 
chemical and lifeless ferments. 
[This paper was intended solely for a local 
niedical society, and not at all for publication. 
It must easily be seen that a question so ex- 
tensive and involved as that of the subject of 
this paper could not be intelligently treated in 
so short a communication. I am sensible 
,that not even a summary has here been given 
—that the question, indeed, has little more 
than been stated.—Chapman.]