A COJSTTEIBUTIOIsr 
TO THE STUDY OF 
THE ETIOLOGY OF SKIN DISEASES. 
READ AT THE MEETING OF THE AMERICAN DERMATOLOGICAL ASSOCIATION AT 
NEW YORK, AUGUST 28, 1879. 
BY 
JAMES C. WHITE, M. D., 
PROFESSOR OF DERMATOLOGY IN HARVARD UNIVERSITY 
[Reprinted from The Boston Medical and Surgical Journal, October 23, 1879.] 
CAMBRIDGE: 
printed at tfje Bibcr^itic 
1879. A CONTRIBUTION 
TO 
THE STUDY OF THE AETIOLOGY OF SKIN DISEASES.1 
BY JAMES C. WHITE, M. D., 
Professor of Dermatology in Harvard University. 
It may seem needless to offer another contribution to this much- 
discussed question, but it is so enveloped in superstition, in popular 
errors descended from past professional beliefs, and in the crude theories 
of physicians, even, of the present day that it must continue to invite 
the active consideration of dermatologists. Unfortunately the opinions 
expressed by our own class in their writings and teachings upon this sub- 
ject show a wider difference to-day than upon any other point in derma- 
tology. Every national school has its peculiar belief, every master his 
individual doctrine, every author his own views, which are promulgated 
with as much positiveness as if such discrepancies of opinion were un- 
heard of. If one could approach the study of dermatology for the first 
time after mature acquaintance with the literature and science of all 
other departments of medicine, he would experience unbounded surprise 
at a peculiarity which surrounds this question of mtiology both in its 
history and present aspect, that is, the tendency to refer the occurrence 
of skin diseases to disorders of all other parts of the economy. It is as 
if it had been the design of all specially concerned to hold and represent 
the skin as guiltless of self-disturbance, functional or structural, as the 
battle-ground on which foreign systems and remote organs elect to work 
off their ill humors, or as a passive mirror to reflect all the morbid 
changes going on beneath its surface. No such exemption from inde- 
pendent capability of disease, no such attributes of purely vicarious dis- 
turbance, are to be found in doctrines held concerning any other depart- 
ment of regional or general medicine. The reasons for this unique 
1 This paper is presented as an elaboration of the opinion briefly expressed in the writer’s 
address before the first meeting of the association : “ We recognize the fact that the skin is 
of itself a great series of complex organs, with just the same inherent tendencies to disease 
and just the same right to its independent affections as the tissues of any other organ. By 
this we do not of course intend to deny that it is a part of and closely connected with the 
general condition of the body in disease, only no more so necessarily than any other of its 
separate parts.” 2 
The JEtiology of Skin Diseases. 
peculiarity in dermatology are to be sought in the superstitions which 
have from remote time surrounded this the oldest field of medical ob- 
servation, and which have clung to it in large measure even to our 
day. The popular and professional names in use in our own and other 
languages to designate the visible structural cnanges in the cutaneous 
tissues in a state of disease are the simple expressions of these primitive 
beliefs. The peccant humors of a past orthodox pathology still flow un- 
changed to the popular mind in their well-worn former channels, and 
announce themselves at will upon the outer surface of the body in tan- 
gible forms. The bad foreign elements within us, in our fluids, in our 
organs, of introduced and inherited origin, seethe up at times, and burst- 
ing through the tegumentary crust which has concealed them appear 
as eruptions upon the skin, marked by the appropriate accompani- 
ments of flaming heat and fluid corruption. These terms, humors, 
eruptions, breaking-out, efflorescence, which had their unequivocal ori- 
gin in the medical profession, and yet retain a quasi-scientific position 
in our nomenclature, have still a positive and literal meaning with the 
vast majority of mankind, even among the most intelligent classes and 
races; and I am sorry to add that I fear that physicians are still in 
some measure responsible for this state of popular belief, and even now 
sympathize with it. Not a year goes by that the specialist is not told 
many times by patients, otherwise well educated, that their family physi- 
cian has advised them to do nothing for this or that skin disease, lest 
interference with its course should be injurious to them. The innumer- 
able times that we must remove the spontaneous fears of all classes of 
society that we may “drive the disease in ” by our remedies, that there 
is danger of its “ striking in,” I need not allude to ; they are one of the 
great obstacles to successful practice in dermatology, and peculiar to it. 
These popular prejudices may be regarded, then, as the direct offspring 
of past and present views among physicians concerning the aetiology 
of skin diseases. They will prevail until the profession discards wholly 
its inherited theories regarding the causation of cutaneous disease, and 
considers the question by the same methods that are now applied in the 
study of this and similar subjects in all other branches of medicine. 
In the first place I proclaim the inherent independence and individu- 
ality of diseases of the skin in as full measure as pertains to those of all 
other parts of the body. Secondly, I maintain that the pathological proc- 
esses which constitute cutaneous disease are identical in nature with those 
which are observed in the tissues of all other parts of the body in sim- 
ilar morbid conditions. Thirdly, the same methods of observation and 
reasoning which are employed in the study of the natural history and 
therapeutics of disease of all other parts of the human economy are 
equally applicable in dermatology. These would seem at first hearing 
self-evident propositions, but nothing is farther from reality than their The JEtiology of Skin Diseases. 
3 
common acceptance as such by physicians. Let us consider briefly their 
professional standing: — 
First, the autonomy of the skin, in as strict a sense as this term may 
be applied to any organs or systems of the body. Who is prepared to 
deny it this right a priori? Perhaps no one absolutely and in a gen- 
eral and theoretical sort of way. Yet it cannot be denied that a large 
number of physicians, and dermatologists even, refuse to recognize such 
independence in their writings and practice. Admitting, of course, the 
existence and individuality of certain affections of the skin caused by 
extraneous agencies, they dispute the independence of identical struct- 
ural changes in it which occur without tangible cause, and hence refer 
most of its ordinary diseases to indefinite and remote agencies. With- 
out mentioning again the popular beliefs just spoken of, which are also 
largely held by the medical profession, it will suffice to refer to the 
theories entertained on this subject by teachers in dermatology. I say 
theories purposely, because the doctrines maintained by them are founded 
almost wholly on pure assumption or' inference ; they do not even at- 
tempt a positive argument in support of their position in most cases. 
They agree in denying the inherent right of the skin to independent 
diseased action, and in failing to recognize that the burden of proof rests 
upon them to show why this is so ; but beyond this common ground of 
negation there is no unanimity or consistency among them. We find 
the most striking diversity in the nature of the theories put forward 
in explanation of skin diseases, according to individual, sectional, and 
national characteristics, but no cumulative weight from common adop- 
tion, because none are based on scientific observation or experiment. 
Each writer seems to rest satisfied that he has established the truth of 
his denial of the local or unconstitutional origin of this or that affection 
by assigning its cause to some remote internal organ, which has respon- 
sibility enough in bearing its own burdens, or to disturbances of this or 
that function, or chemical changes in circulating fluids, the mere exist- 
ence of which of themselves may not even be well established, or to 
some still more chimerical and intangible vice of the economy. Ordi- 
narily the inventors or supporters of these theories are content with a 
simple assertion, as just stated, of their soundness, and only exception- 
ally make an attempt to back them by a presentation of evidence which 
can be properly tested by recognized methods of analysis. 
Of the former class the astiological doctrines of the French school of 
dermatology offer the most striking illustration. It may be, perhaps, 
unfair for any one not a Frenchman to venture to discuss the merits of 
the dartrous diathesis, for instance, for no one else has ever seen evi- 
dence of its existence; yet here are men who for half a century have 
occupied the most prominent positions as leaders in one of the greatest 
schools of dermatology, believing not only in the corporeal reality of 
such a demon as la dartre, but that it is the cause of most of the skin 4 
The jEtiology of Skin Diseases. 
disease which affects mankind. Yet ask them to define its nature, and 
they give you merely a description of the symptoms common to the 
affections which they say it causes. It is in fact very like the evil 
spirits which the medicine-men of barbarous races exorcise, and its con- 
tinued hold upon the mind of scientific men of that civilized people can 
be explained only on the supposition of a transmitted and irresistible 
mental quality or strain, as national doctrines in theology are perpetu- 
ated. Another illustration of this class may be found in the disposition 
to refer the causation of skin diseases universally prevalent to the action 
of certain diseased conditions of the economy, or of extraneous influ- 
ences which are necessarily sectional or restricted in their occurrence. 
If we cross from France into England, where gout is very prevalent, 
we shall find that this affection is regarded by dermatologists as the 
most important factor in the causation of many skin diseases, and that 
in their writings they in no way restrict its action in this respect to 
their occurrence at home, but assign it a universal influence. Yet gout 
is a very rare condition in some other parts of the world, where these 
cutaneous diseases prevail as frequently and manifest themselves of the 
same type as in England. A similar example presents itself here at 
home in our own transactions: one of our number has announced the 
dogma that all skin diseases in all regions geographical are the result of 
two causes only, — the chronic of scrofula, the acute of malaria. With 
regard to the first of these nothing will be said in this connection, but 
as to the second it is known that malaria, as generally understood, is 
confined to sharply defined geographical districts. It is as well known 
that the cutaneous affections which, it is claimed, are due to its influ- 
ence prevail most extensively in regions where malaria does not practi- 
cally exist. How, then, shall we explain the promulgation of opinions 
in aetiology which seem to bear on their face such apparently self-evi- 
dent confutation ? How else than on the supposition that, overbalanced 
by observing the almost general occurrence of these endemic affections 
at home, they should misjudge their frequent manifestations in connec- 
tion with the more common skin diseases, and, magnifying mere coin- 
cidence into essential cause, proclaim their inferences from restricted 
observation as facts of world-wide application. 
Of the second class, those who attempt to present evidence of the 
soundness of their theories, it is a fair representation of its character in 
nearly every instance to say that the proofs offered rest here, too, al- 
most wholly upon inference or coincidence. Take, for instance, those 
who would support on scientific grounds the old and ever popular theory 
that skin diseases are caused by disordered states of the blood. Mere 
assertion on this point is of course worth no more in this connection 
from the physician than from the people. We require proof, first, that 
the blood is disordered ; then, that such morbid conditions of this fluid 
are constant in these affections, and that they never occur where this The JEtiology of Skin Diseases. 
5 
condition is not coexistent. With regard to the first, evidence would 
be admissible bearing upon its physical, chemical, or morphological con- 
stitution ; the second demand could be conclusively answered only by 
the application of these tests to a very great number of cases. I am 
not aware that any of the dermatologists who actively support this hy- 
pothesis have any such data to present. Direct analyses of the blood 
have been made in connection with certain rare and peculiar forms of 
skin diseases, which from certain characteristics have been thought to 
be dependent upon disordered states of the circulating fluid ; but in all 
cases the results obtained were unsatisfactory and negative. They offer 
no such direct methods of research, but in place of them resort to the 
examination of other fluids or secretions, and offer any abnormal condi- 
tion of the latter they may find as conclusive not only of the disordered 
state of the blood, but as establishing the immediate relation of cause 
and effect between the state of blood and skin. The urine has natu- 
rally been selected as the most ready means of demonstrating such 
relationship, and I may be permitted to repeat here what I have else- 
where written: that there can be no question as to the intimate physio- 
logical relations between the kidneys and the skin in health, or of the 
occurrence of infrequent changes in the tissues of the latter when its 
circulation is surcharged with products which the kidneys have failed 
to eliminate, or of coincident disturbances in both in some constitu- 
tional affections. That the skin may thus occasionally be studied as an 
aid to diagnosis in renal disease, and in certain changes in the economy 
which announce themselves by synchronous modifications in the com- 
position of the blood and urine, is true ; but this does not warrant the 
inference that all variations in the urine which are found associated 
wdtli skin diseases stand in any intimate relationship with them, or that 
they are both the common expression of some causative blood disorder. 
In fact, the changes in the urine of patients with skin diseases which 
have been observed are of a trivial character in the main, and such as 
occur in the most various and unimportant conditions of the economy, 
and can in no way be regarded as characteristic of the cutaneous affec- 
tions in which they have been recorded. The results obtained from 
an extensive analysis of urine from the skin w'ard of a great general 
hospital would differ little, if at all, I doubt not, from those which any 
general ward would furnish, or such as would be obtained by no means 
infrequently in the examination of the urine from the same number of 
apparently healthy people. This is my own experience from the study 
of the urine in health and in disease. It is well to call to our aid so 
exact a science as chemistry in this study of mtiology, but all chances 
of error must be excluded in its application, and its teachings not be 
misinterpreted, if conclusions are to be drawn from it affecting the ques- 
tion of the relations of skin diseases to the blood or general economy. 
Concerning the hold which several of these theories have upon the 6 
The TEtiology of Skin Diseases. 
convictions of some dermatologists we may qnote the recent words of 
Huxley: “ As none of these hypotheses is capable of even an approxi- 
mation to demonstration, it is almost needless to remark that they have 
been severally held with tenacity and advocated with passion.” 
Second. The pathological processes which are found in the structural 
lesions and functional disturbances of the skin are in no way peculiar 
to the cutaneous tissues. I think that all are willing to accept this prop- 
osition who have made themselves familiar with the results of recent 
investigations into the pathological anatomy of the skin, or who have 
made independent studies in this direction. This subject has been so 
completely neglected by the profession generally until within late years 
that there has been no opportunity for the establishment of prejudice or 
wrong opinion on their part, at least, regarding it; and although hasty 
conclusions by observers in this field have not been wanting, accumu- 
lated results only add to the certainty of the unity of morbid processes 
in all parts of the human organism. It may be most positively stated 
that those who would establish an exceptional system of astiology for 
cutaneous disease out of analogy with that which applies to all other 
parts of our frame will find no heterogene basis for its support in the 
teachings of pathology. 
Third. The same methods of observation and induction should be 
employed in the study of this question in dermatology as are deemed 
legitimate and essential in similar investigations in general medicine. 
What results, then, do such methods of research yield when applied to 
this inquiry: In what relation does the skin stand to the other organs 
of the economy that its structural changes and functional disturbances 
are in any way dependent upon them ? Let us consider briefly what 
we really know concerning any such connection in respect to the most 
important of these organs. 
Brain and Nervous System. Of late years it has become the fashion 
among writers on dermatology to refer many affections of the skin, the 
causes of which are not satisfactorily understood, to disturbances of the 
nervous system. I say fashion purposely, because such reference is of 
quite recent origin, and because positive data for such conclusions have 
not multiplied within the same period, and are in fact most scanty and 
incomplete. That we have been able to trace the terminal cutaneous 
nerves a little farther towards the periphery, so as to recognize their 
distribution among the cells of the rete ; that certain moderate disturb- 
ances of sensibility accompany the dermal tissue changes in a few dis- 
eases of the skin; that some forms of new growth and hypertrophy of 
the cutaneous tissues develop along certain nerve tracts ; that the irri- 
tation of the peripheral nerves of one portion of the external surface 
may excite an irritation or an eruption'upon distant parts of the integu- 
ment by reflex action, as we say ; that injuries to the trunk of a nerve 
may give rise to a variety of efflorescences upon that portion of the skin The JEtiology of Skin Diseases. 
supplied by it; and that disease in the ganglion or neurilemma may be 
followed by a definite sequence of inflammatory phenomena in the 
structure of the overlying skin, we have learned. But this is very little 
upon which to found a division in classification so comprehensive as 
some would make the neuroses in their systems of nosology, or to war- 
rant so frequent an appeal to the nervous system in discussing the 
aetiology of skin diseases. The terms trophoneurosis, faulty innervation, 
reflex irritation, etc., are used coupled with many affections with the 
most slanderous looseness, where not the slightest positive proof of such 
connection is offered, or scientific grounds for such inference exist. 
What does “ faulty innervation,” for instance, mean without some dis- 
coverable tissue change in the nerve structures ? What satisfaction 
can such an expression afford to the truth-seeker in mtiology when ap- 
plied to the common diseases of the skin? We know that along the 
nerve fibres come those messages which regulate the circulation, con- 
trol the vital processes of every part of the skin ; but in the same way 
are governed the tissues of every other„part of our frame, and unless 
we are prepared also to attribute all corporeal pathological processes to 
faulty innervation with as little reason as in dermatology, let us stop 
our meaningless talk about it here, too. We do not visit hospitals for 
diseased nervous systems to study skin diseases, nor do insane asylums 
present any characteristic cutaneous affections where the general func- 
tions of the inmates are properly cared for. That condition of physical 
misery-with its cutaneous manifestations called pellagra, so common in 
the immense pauper mad-houses of Europe, never occurs in our asylums, 
and can therefore have no real connection with lesions of the central 
nervous system. If we cannot discuss aetiology without guessing, let us 
do this at least with some show of reason. Neuro-pathology is still a 
suckling itself, and affords little support to dermatology in this regard. 
Lungs. Although the lungs, like the kidneys, have one function in 
common with the skin, that of the removal of water from the economy, 
yet on this ground of connection or otherwise but a small part has been 
allotted them in the causation of the diseases of the latter, either directly 
or indirectly. Even in that most universal and destructive of all dis- 
eases, consumption, the skin undergoes but little change throughout its 
most protracted course, and specific disorders in connection with it do 
not occur. Two affections, however, it has been frequently asserted, 
are somewhat intimately associated with it, or the general condition to 
which it gives rise, namely, lichen scrofulosorum and tinea versicolor. 
The former, by no means of uncommon occurrence in Germany among 
the miserable classes so frequently subject to so-called scrofula and con- 
sumption, is rarely seen with us, although the latter is so generally 
prevalent in all classes. According to the tabulated statistics of thirty- 
two thousand cases of skin disease recorded by American dermatolo- 
gists, it has been observed but seven times in this large number. Is it 8 
The of Skin Diseases. 
anything more than a condition of life-long neglect of the skin, becom- 
ing more prominent when the cutaneous tissues are devitalized by the 
marasmus incident to the affections with which it has been associated? 
Tinea versicolor, too, is believed by some dermatologists to have more 
than a casual relation to consumption, and by others at least to flourish 
best upon those whose systems are reduced by such wasting disease. 
With these opinions I cannot agree in any measure. I do not believe 
that any of the vegetable parasites of the skin require a special charac- 
ter of cutaneous soil, such as is imparted to it by disease of any kind, 
local or general. They flourish, according to my observation, upon all 
alike, so far at least as the health of the individual is concerned, and 
any theory which presupposes certain conditions of the skin or economy 
as essential to their development must be classed with that old belief 
in the itch dyscrasy. I once had the opportunity of studying the spread 
of tinea trichophytina in a large orphan asylum, whose inmates had for 
years been under the care of a dermatologist who had accepted as un- 
questionable the dogma of Mr. Wilson, that it was not of parasitic nature. 
The disease had had, therefore, no anti-parasitic treatment, and had 
attached itself to some forty children. It showed, however, no especial 
affinity for the weak ones among them in its early stages, nor failed in 
the most robust to develop into the deeper-seated and later forms upon 
the hairy parts; and its action under treatment upon the scalp was 
alike obstinate in both classes. Imported into family life by the adop- 
tion of these orphans, it never failed, where traced, to transplant itself 
upon the most healthy members of the household. The same readiness 
to universal transplantation is seen in the history of its introduction into 
a large family through the domestic animals. In the two cases reported 
by me in the Journal February 14, 1878, every member of the family 
who handled the kittens became at once affected by ringworm. Ex- 
amples of this impartial selection might be indefinitely multiplied. So, 
too, with tinea versicolor; although by no means as common, because 
growing under cover, or as easily communicated, as tinea trichophytina, 
yet it attaches itself and grows with the greatest luxuriance and for 
years upon the most robust and cleanly adults. It does not, however, 
spare the sickly, and that it is so frequently found upon the consump- 
tive is simpl}'' because its discovery is insured by the exposure of the 
chest under examination. Such incidental connection shows only that 
the disease is much more common than is evident from the confessions 
or complaints of those affected by it. 
The connection of asthma with eczema is often referred to in corrob- 
oration by those who possess a prominent belief in the constitutional 
nature of skin diseases, as if both affections were the expression of 
some common general vice of the economy. But this connection is 
rarely exhibited, like that with rheumatism, and is at most an alternation The JEtiology of Skin Diseases. 
9 
such as is often observed between other diseases which are not claimed 
to have any mutual relationship. 
Heart. To this organ and its disorders no one has allotted any im- 
portant share, to my knowledge, in the causation of skin diseases, chief 
engine as it is for the propulsion of a fluid impregnated, in popular and 
professional belief, with such intense capabilities in this direction. 
Stomach. Not so innocent in this respect, however, are the organs 
of digestion regarded. Admitting the prompt and active impression 
upon the skin of certain substances called irritants when introduced 
into the intestinal canal of exceptional individuals, I am not prepared 
to accept the agency so commonly assigned, even by dermatologists, to 
these organs in the production of other cutaneous diseases. Arguing 
from these forms of erythema and urticaria resulting from gastric irri- 
tation, so called, many are disposed to assign to various articles of food 
an active part in the causation of some of the most common affections, 
even when no immediate effects are produced upon digestion or skin. 
Thus butter, fish, oatmeal, buckwheat, etc., are popularly believed to 
give rise to eruptions, and are generally forbidden on this account dur- 
ing the course of acne and eczema. Even dermatologists of a certain 
school share in this belief, and instruct their patients liable to the latter 
that fish is never to be eaten by them. The proper way to substan- 
tiate such opinions or prejudices would be to show either that these 
affections are more frequent or severe among nations which make a 
very large or almost exclusive use of such articles of food, or that 
attacks of these diseases are directly induced or aggravated in individ- 
ual cases by their consumption. Such demonstration has not been 
made, and I believe is impossible. In my own experience, founded 
upon the latter test, these substances are perfectly incapable of such 
influence upon the skin. I believe also that too much importance is 
attached to positive disturbances of digestion as a factor in cutaneous 
aetiology. With regard to the other disease above mentioned, for in- 
stance acne, we are told in several recent treatises and papers that the 
two conditions are not only well-nigh inseparable, but that the visible 
presence of the eruption is a necessary evidence of the existence of the 
indigestion, although every ordinary manifestation of the latter be 
wanting. Now I desire here to express my dissent, both from the facts 
as thus presented and such methods of reasoning from them. Acne 
between the ages of fourteen and twenty in both sexes is extremely 
common, and forms eighteen per cent, of all cases of cutaneous disease 
in mv private practice. Indigestion, or dyspepsia, is a disorder cer- 
tainlv as common amongst us at all ages of life, but certainly not most so 
at this particular period. It is evident, then, that if it cause acne at 
this age chiefly and not at others, it is due to other agencies cooperative 
then and not at other times. We have therefore at the start to recog- 10 
The TEtiology of Skin Diseases. 
nize another element wholly apart from the digestive disturbance. 
But are there in fact any legitimate grounds for thus connecting the 
conditions as cause and effect ? Does acne occur in any large per- 
centage of persons, even at the most favorable age for its develop- 
ment, affected by any forms of indigestion ? Do all acne patients, on 
the other hand, suffer from disturbances of the digestive functions ? 
Enter any large general hospital, or consult the extensive records of its 
out-patient department, and note the vast numbers of patients afflicted 
with one or more of the varieties of indigestion, alone or in connection 
with other forms of disease, and how infrequently you will find acne 
amongst them. Yet a 'priori there is as much reason for attributing to 
the former all the manifold ills with which it is associated as the acne 
occasionally met with, namely, that of coincidence. Tested by the 
second and more direct inquiry, however, what positive evidence is 
gained? Do patients with acne suffer from indigestion in any marked 
degree or frequency, and, if coexistent, is the former affection due to the 
latter? I do not hesitate to answer both questions in the negative. I have 
made a careful and special examination of every patient with this dis- 
ease seen by me in private and dispensary practice during the past two 
years with reference to this point. I find a very small percentage of 
them, chiefly among the latter, affected by some form of primary indi- 
gestion, and a larger proportion exhibiting more or less a habit of con- 
stipation ; yet both faults occurring no more frequently than among an 
equal number of persons under the same condition of life unaffected by 
acne, certainly not oftener than in connection with other affections of 
the skin or the remaining organs of the body. I find, however, by 
far the larger portion of them, especially in private practice, perfectly 
healthy persons, as sound in every way, but for the local follicular in- 
flammation, as humanity admits of, — that is, if we are to be permitted to 
gauge our judgment in this respect by the ordinary means of analysis. 
If, however, we are to be told that such methods of investigation are 
out of place in this question, and that the mere presence of acne efflo- 
rescence, a priori and of necessity, proves the contrary, I must confess 
myself incapable of meeting such arguments on their own ground. 
Again, if we appeal to therapeutics, what answer do we obtain ? Do 
we find in the majority of cases where the cutaneous and intestinal 
disorders do coexist that the relief of the latter is followed by the dis- 
appearance of the other ? I have tested this thoroughly, I think, and 
am sustained more strongly in my position. I do not find that the coin- 
cidence of the two affections influences the probable course of the dis- 
ease of the skin under treatment. I doubt if any member of this asso- 
ciation feels warranted in offering a more positive or favorable progno- 
sis because the alimentary symptoms are especially marked in any indi- 
vidual case over those cases in which they are absent or masked to 
ordinary means of recognition. Do we find obstinate, inveterate cases The JEtiology of Sldn Diseases. 
11 
of juvenile acne yielding to remedies addressed to faulty digestion ? Are 
we not compelled to treat them, if indeed we are permitted, long be- 
yond the period when they would have been dismissed, had we been 
consulted merely for the internal disturbance ? I at least must ac- 
knowledge my inefficiency before the disease to this extent, and I never 
fail to treat this or any coexisting evil which may in any way obstruct 
its cure, even if in no way its cause. While denying, then, any impor- 
tant action in this respect to functional disturbances of digestion, which 
affect a great majority of mankind in some degree without producing 
such effects, and which, on the other hand, are absent in any apprecia- 
ble measure throughout the clinical history of a majority of individual 
cases of acne, I must still confess a profound ignorance as to its mtiology. 
Liver. It is somewhat remarkable, considering how prone mankind 
has been to regard its liver as the cause of much of its ill health, that it 
has had so small a share assigned it in the causation of cutaneous disease. 
There still lingers in the professional creed to a considerable extent the 
belief that it is responsible for the existence of tinea versicolor and some 
forms of chloasma. How such an error could have arisen it is impossible 
to understand, unless from poor guess-work and the ruling tendency 
among physicians to fall back upon the imagination rather than confess ig- 
norance when questioned concerning the causes of disease, — a trait which 
has been a constant obstruction to progress in aetiology. The imagination 
may indeed be of vast service in science, bearing the mind involun- 
tarily beyond the bounds of conscious action to meet great truths half- 
way, but only when previously trained to flight by constant exercise 
under the fundamental laws of true philosophy. Recently an unwar- 
ranted charge has been made against the liver in connection with xan- 
tlioma (xanthelasma, vitiligoidea), some of the English writers assigning 
to it an essential part in the development of this uncommon affection. 
This role, however, must be only a casual one, for in ten cases carefully 
examined by me with regard to such association there was not the 
slightest basis for such an opinion. 
Kidneys. These organs, too, considering their important duties in 
the economy and their close supplementary relations with the skin, have 
preserved a marked exemption from accusations of contributing to the 
causes of its diseases. The relations of the urine to this question have 
already been sufficiently discussed elsewhere, as it is not claimed by 
those who urge their importance that they implicate the kidneys as dis- 
tinct factors in any way, these organs merely eliminating tor our exam- 
ination the evidences of preexisting disturbed relations between the 
skin and blood. That organic disease of the kidneys may exist for long 
periods, and be complicated by grave structural changes in several 
other important organs and leave the skin and its functions so free from 
disorder, illustrates in a striking manner what I have been insisting upon 
throughout this paper, — its marked independence in health and disease. 12 
The JEtiology of Skin Diseases. 
Reproductive Organs. There can be no doubt that the skin shares 
to some extent in the general excitement of the system dependent upon 
its ripening into puberty in both sexes, and sympathizes in a very slight 
degree with its disturbances at the climacteric age in women. The 
close relations of the integument to these organs in the lower animals 
especially is seen in the wonderful changes it exhibits during their peri- 
odic fluctuations of sexual activity. The astonishing coruscations of 
pigment and rapid tissue development manifested in its appendages, 
scales, feathers, hairs, and the like at such periods constantly excite our 
wonder. In the mammalia, even in the highest order below mankind, 
we find marked examples of similar fluctuations in the cutaneous struct- 
ures during the rutting season. It is not strange, therefore, that during 
the rapid development of the follicular structures, the hair and odorif- 
erous glands, in this awakening period of sexual power in our own youth, 
termed puberty, disorders should likewise frequently manifest themselves 
in the associate glands, varying in severity from simple oversecretion to 
destructive inflammation. From such normal relations it is fair, perhaps, 
to infer that unnatural and diseased excitements of the sexual system 
may give rise to similar disturbances in the cutaneous structures. The 
fact that acne most generally comes on at the beginning of puberty, 
and is most troublesome during the period of uncertain sexual relations 
between that and marriage ; that it sometimes disappears on the restora- 
tion of irregular menstruation ; that it has been observed apparently 
with unusual frequency in institutions devoted to celibacy and the wor- 
ship of Vesta, while it is supposed to spare the inmates of those devoted 
to the purposes of a mercenary Venus; that eunuchs are reported as 
remarkably exempt, and that it is supposed to be a symptom of onan- 
ism, has led to a quite generally entertained opinion that it is in some 
way connected with, if not dependent upon, the functions of generation. 
It is an opinion, however, which is based on data peculiarly uncertain 
and liable to error, because beyond the sphere of accurate scientific 
investigation ; and although there is undoubtedly some degree of truth 
in it, there are so many and so striking facts of rebutting character that 
it must not be received as founded upon definite and satisfactory evi- 
dence. 
Thus I have endeavored to show some of the difficulties and errors 
which envelop the study of cutaneous aetiology: in part, prejudices 
born of ignorance, but of strange vitality, and transmitted with the 
authority of both popular and professional belief; in part, the direct 
result of hasty, short-sighted theorizing by those who occupy the posi- 
tion of teachers in our art. We shall make no real progress in this 
branch of dermatology until we sweep away all this rubbish of super- 
stition, all these crude theories of schools and writers, and professing 
entire ignorance, if need be, build up a true astiology by legitimate 
touihods of truthful observation and sound reasoning.