BIOLOGY
LIBRARY

HEREDITY: A STUDY.

HEREDITY :

A STUDY;
WITH SPECIAL REFERENCE TO DISEASE.

BY

R. A. DOUGLAS LITHGOW,

LL.D., F.S.A., F.R.S.L., F.R.G.S.I., M.R.C.P., L.R.C.S. ED.,
L.S.A. LOND., ETC.,

MEMB. OF COUNCIL R.S.L. J MEMB. OF COUNCIL BRITISH ARCHAEOLOGICAL SOCIETY J MEMB.

MANCHESTER LITERARY CLUB J MEMP. FRITISH MEDICAL ASSOCIATION;

FFi.LOW OF THE OBSTETRICAL SOCIETY, ETC.

" I have been dealing with old names and well-established doctrines, and
my reason lor bringing them before you has been, not so much the hope of being
able to contribute new facts or theories of my own, as the desire to set in better
order that floating knowledge which is a gene;-a> possession."

Mr. Jonathan Hutchin son's " Pedigree of Disease."

LONDON :

BAILLIERE, TINDALL, AND COX,

20, KING WILLIAM STREET, STRAND,

1880.

TO

JONATHAN HUTCHINSON, F.R.S., F.R.C.S.,

ETC., ETC.,

AN ACCOMPLISHED SURGEON,— AN ORIGINAL THINKER, —
A GRACEFUL WRITER,

WHO

HAS DONE, PERHAPS, MORE THAN ANY OTHER LIVING AUTHORITY

TO PROVE THE INFLUENCE OF HEREDITY IN PATHOLOGICAL

PROCESSES,

THIS LITTLE BOOK

is,

(BY PERMISSION)
MOST RESPECTFULLY AND ADMIRINGLY

DEDICATED

IN TOKEN OF
MANY PERSONAL KINDNESSES.

357753

PREFACE.

HE contents of this little volume first appeared in the PROVINCIAL
MEDICAL JOURNAL during the years 1887 and 1888, under the
title of " From Generation to Generation : a Prelude to the Study of
Heredity ;" but inasmuch as I found that I had been anticipated in the
first part of this heading, I have, for obvious reasons, altered it to the
present title, although I still prefer the former as indicating better the
character I claim for the work — viz., a mere outline of the subject.

For many years past I have taken much interest in the question of
Heredity, and have thus accumulated an immense quantity of information
concerning it. The following pages contain the merest outlines of the
physiological and psychological aspects of the subject, although I take
some credit to myself for making, what I believe to be, the first
systematic effort to trace the influence of Heredity in all the main
diseases which afflict humanity.

Wherever possible, I have chosen rather to quote from the greatest
authorities, than to detail in my own words the many interesting facts
referred to ; thus presenting a picture in which the lights and shadows
have been added by the great Masters to the sketch of the Student.

If I am successful in evolving a deeper lay and professional interest
than has hitherto been taken in a subject so intimately concerning the
welfare of both classes, I shall be more than repaid for having made
the effort.

27A, Lowndes Street,

Belgrade Square, S. W. ,

April, 1889.

FROM GENERATION TO GENERATION:
A PRELUDE TO THE STUDY OF HEREDITY.

HEREDITY -is one of the fundamental laws underlying
the grand scheme of evolution ; and without the former,
the latter would lose all its significance and force, for by
its action the development and perpetuation of species is
maintained amid incessant variation, and all organised
beings tend to repeat themselves in their descendants.
As Ribot says : " Heredity and evolution are the two
necessary factors of every stable modification in the
domain of life. Suppose evolution without heredity, and
every change becomes transitory, every modification what-
ever, whether of good or bad, useful or hurtful, disappears
with the individual. . . . Suppose heredity without
evolution, and there is nothing but the monotonous
conservation of the same types, fixed once for all. Phy-
siological characters and instincts, intellectual and moral
faculties, are preserved and transmitted without modifica-
tion. . . . On the other hand, suppose both evolution
and heredity, and then life and variation become possible.
Evolution produces physiological and psychological modi-
fications, habit fixes these in the individual, heredity fixes
them in the race." Considered ideally, heredity would
be a simple question of like begetting its like, but this
is not so, as vital phenomena are not characterised by
such rigorous exactitude, the modifications of their exist-
ence tending to become more and more complex as we
ascend from the vegetable to the animal world, up to man
himself.

A

T-il f&;

The phenomena of heredity, in a general sense at least,
have been observed by all people at every age of the world's
history. Thus in the ancient and sacred laws of Manu, we
find the following aphorisms : — " A woman always brings
into the world a son gifted with the same qualities as he
who begat him." "We may know by his- acts the man
that belongs to a low class, or who is born of a disre-
putable mother." " A man of low birth has the evil
disposition of his father, or of his mother, or of both — he
can never hide his descent." So also in the Mosaic law : —
" I, the Lord, thy God, am a jealous God, visiting the
iniquities of the fathers upon the children to the third
and fourth generation, etc." Elsewhere in the Bible we
read: — "When the fathers have eaten sour grapes, the
children's teeth are set on edge." The well-known lines
of Horace are as follows : —

" Fortes creantur fortibus et bonis
Est in juvencis est in equis patrum
Virtus, nee imbellem feroces
Progenerant acquiloe columbam."

Horace, Lib. iv. , Ode 4.

Lastly also, Goethe, in his Iphigenia : —

" How blest is he who his progenitors

With pride remembers, to the listener tells
The story of their greatness, of their deeds,
And, silently rejoicing, sees himself
The latest link of this illustrious chain !
For seldom does the selfsame stock produce
The monster and the demigod : a line
Of good or evil ushers in at last
The glory or the terror of the world."

The Lamarckian axiom that "Like produces like" can
only be regarded as a generalization, which however true as
such, yet when subjected to minute examination is found to
be erroneous, inasmuch as the tendency of like to produce

like is not only modified by the influence of external cir-
cumstances, but to a still greater extent by that tendency
to variation which is manifested in all animals, and which
Darwin regarded as the greatest argument in favour of his
theory of evolution. There are in fact no two beings pre-
cisely alike ; brothers and sisters present many differences ;
and even were they formed according to the undisturbed
force of hereditary transmission, endless diversifications
would result from inevitable diversities of proportion of
transmission, parental, as well as ancestral. The operation
of hereditary tendencies is perpetually disturbed by innu-
merable circumstances too subtle for us to appreciate, and
yet capable of producing varieties infinite alike in extent
and degree. How these spontaneous differences occur we
cannot tell ; but that individual varieties are transmissible,
and capable of producing new races in domesticated animals
by artificial selection is indisputable ; and in the human
family the tendency to spontaneous variation i» even still
greater.

I now propose to view heredity in its physiological, psy-
chological, and pathological aspects, and in the space at
my disposal to give at least some general idea of this most
important biological law.

There are few natural phenomena more interesting and
marvellous than those affecting inherited peculiarities of
feature, figure, character, constitution, habits, etc., and their
perpetuation, and the numerous facts of hereditary trans-
mission are all the more wonderful when we contrast them
with other and better-known phenomena, which experience
and scientific progress have enabled us to group under cer-
tain definite laws. The laws of planetary motion are recog-
nised, and to a great extent understood ; the systematic

8

order of chemical changes is appreciated with scientific
precision, and the phenomena of heat, light, and electricity
are gradually being unfolded and revealed. The phenomena
of inheritance, however, although recognised to some extent,
as I have said, from the earliest ages, have but recently been
subjected to such analysis as enables us to refer them to a
biological law ; and, notwithstanding that this must be
regarded as a later, and less perfect revelation, when com-
pared with the other sets of phenomena to which I have
alluded, yet the phenomena of inheritance are by degrees
finding interpretation, and in all probability the grand law of
heredity will ere long be as well recognised, and as firmly
established as any of the so-called laws of the universe.
" Natural laws," says Dr. Carpenter, " can only be regarded
as the general expression of the conditions under which
certain assemblages of phenomena occur, so far as those
conditions are known to us ;" or in the words of Mr. Lewis,
"the paths along which forces travel to their particular
results." If phenomena be reducible to a law, their inves-
tigation constitutes a science. Science can only deal with
phenomena and experience ; and when we come to regard
the ultimate causes of any of these groups of natural phe-
nomena, and find them not reducible to law, they must be
attributed to the supernatural, as science pauses paralysed
at the very threshold of such an inquiry. The conditions
under which the phenomena of inheritance occur, in so far
as they are known, enable us to group these phenomena so
that their general expression represents a law ; and in pro-
portion as these groups can be accurately defined and in-
terpreted, they are the effects of the biological law of here-
dity, just as the phenomena of gravity are of the great law
of gravitation.

All natural laws are mysterious when an attempt is made
to trace them to their real cause. " It is the office of
science," says Bacon, " to shorten the long turnings and
windings of experience." It is also the office of science
to interpret the " how ;" but the "why " is inscrutable and
far beyond the powers of her revelation. As an anonymous
writer has well said : " Gravity is a mystery of mysteries
to the astronomer, and has almost compelled us to believe
in that ' action at a distance ' which Newton asserted to be
unimaginable by anyone with a competent power of reason-
ing about things philosophical. The ultimate cause of chemi-
cal changes is as great a mystery now as it was when the
four elements were believed in. And the nature of the ether
itself, in which the undulations of heat, light, and electricity
are transmitted, is utterly mysterious, even to those
students of science who have been most successful in
determining the laws according to which the undulations
proceed. But the phenomena themselves, being at once
referable (in our own time, at least) to law, have no longer
the mysterious, and in a sense miraculous, character recog-
nised in them before the laws of motion, of chemical affinity,
of light, and heat, and electricity had been ascertained."
It has been said that all our scientific knowledge, however
coherent, however solid and fruitful in results, is like a gold
chain of which we do not see the first link. Science regards
each link in the chain of phenomena, records the facts, and
interprets the power and purpose of each succeeding link.
By analysis and synthesis, by induction and deduction, she
groups the facts and phenomena into laws, and by the
grouping of laws reveals the wonders of the universe ; and
thus, as Mivart says, " Our appreciation and comprehension
of the world around us is but a continued repetition, on an

10

ever-widening scale, of successive processes of analysis and
synthesis. In each branch of science, along with our keener
and keener perception of differences, we come to perceive
more and more recondite relations of agreement."

I have stated that heredity is a physiological law ; but it
is a law within a law, being in a sense the effect of genera-
tion. The phenomena of inheritance have not only been
observed, but the conditions realized ; and the analysis of
these has indicated where we must seek for the laws of
which heredity is the manifestation — laws which are subject
to variation and individuation as other natural laws. Phy-
siological heredity must be regarded as a physiological
necessity of our being inseparably connected with the great
law of reproduction, the process of which, although very
imperfectly understood up to a comparatively recent period,
has still more recently been brought much more within our
comprehension, notwithstanding that our knowledge of its
nature and functions is even yet incomplete. The respec-
tive characteristics and interdependence of reproduction
and nutrition, long recognized, are now more fully mani-
fested ; and nutrition has been correctly defined as "a
perpetual reproduction."

This would be the place wherein to discuss the minute
details of the reproductive process so far as they are known ;
but as this would be beyond the scope of the present work,
I can only refer the reader to the many and excellent
text-books of physiology and embryology which the progress
of science has rendered far in advance of their prede-
cessors.

The generation of life from life is a mystery which science
has not, and, perhaps, may never solve — a mystery in which
many more mysteries are hidden — and amongst the latter

II

few more mysterious than those of hereditary transmission.
Around, but outside, these arcana of nature, science is
earnestly at work — seeking, recording— analysing, general-
izing, and determined to force from even the heart of Nature
her most hidden mysteries, if within the possibility of
human achievement ; but until her eye is enabled to see far
deeper than heretofore into that which is as yet inscrutable,
the mighty problems of generation and transmission must
remain unsolved, whilst those who follow in the train of
science must, in the meantime, content themselves with
general conclusions justified by phenomena, whilst they
hopefully await the result.

Within two minute cells — one the " sperm-cell " of
the male, the other the " germ-cell " of the female, and as
such different in nowise from any other cells, so far as can
be ascertained by any human power of analysis — and by
whose fusion the "embryonic vesicle" is produced, lie
hidden the mysteries of generation and heredity ; and
science, with all her powers, can reduce them no further.
Take these two little cells as representing a point equally
dividing a right line, at each end of which is the barrier of
infinity. From this point in one direction we follow man
from the cell and its development, through uterine existence,
and having within him the transmitted qualities of his
parents and ancestry — pKysical, intellectual, and moral —
acquiring individual modifications which will in turn be
transmitted to his descendants, — through all the mazes
of his life, for weal or woe, with all life's power and
purpose, until the destiny of his humanity is fulfilled,
and he goes down into the " Valley of the Shadow,"
having left his impress on his survivors, and into the
presence of the Infinite ! From the same point in the

12

other direction, we may resolve the cells into molecules,
and the molecules into atoms, and down, down, deeper,
until, if possible, we reach the ultimate monad — the
ptyeOr) aSicupera, amid the properties or endowments mani-
festly in the very nature of the ultimate fractional . parts of
matter, but the mystery of life is unsolved, and beyond
life is Infinity.

In seeking for the physiological causes of heredity, it
will thus be seen that they are bound up with the mysteries
of generation, and in either case we have reached the
ultimate revelation of science when we regard the fusion
of two simple cells as resulting in the production of a
compound cell — the " embryonic vesicle " — within which
are enshrined the mysteries of reproduction and heredity.

All the elements and functions of the human body are
subject to heredity — internal as well as external — its
peculiarities, diseases, and even acquired modifications.

The likeness between parents and children is a matter of
daily observation, not only as to form, feature, and expres-
sion, but also as regards the peculiarities of the limbs,
trunk, head, nails, hair, skin, complexion, gait, voice,
temperament, etc. That family likenesses will continue for
ages may readily be seen from family portraits when they
have been preserved for many generations ; and, although
seemingly lost in one generation, they will assuredly become
manifest in a succeeding one. The phenomena of the
external structure — those affecting the features and outward
configuration of the body — although comparatively more
common and of less engrossing interest, are not, neverthe-
less, the least instructive. The facts concerning the
hereditary characteristics have, as has already been stated,
been recognised from time immemorial by all peoples and

13

in every age ; hence the amazing peculiarity of the Jewish
race, whose recognition of the force of heredity is shown by
their having, at an early period, founded part of their
judicial system in accordance with the observed transmission
of physical, intellectual, and moral peculiarities from parents
to children. The Greeks, also, were fully conversant with
these phenomena, and the Spartans, regarding them as of
still greater importance, actually made a selection from their
newly-born children, thus endeavouring to secure only the
" survival of the fittest ! " The Romans, likewise, distin-
guished families by their hereditary peculiarities, denomina-
ting them on account of physical characteristics as nasones,
or big-nosed ; labeones, or thick-lipped ; the buccones, or
swollen-cheeked ; and the capitones, or big-headed. The
facts concerning the transmission of family likenesses, and
of general characteristic resemblances which descend from
ancestry and parents to children are so well and universally
recognised that I need not now dwell upon them further ;
they may be observed in every family, and wherever there
are parents and children may be studied with much interest,
not only as to the inheritance of family characteristics, but
with special regard to the still more curious phenomena of
individual peculiarities. It may here be observed that
children, whose likeness to their mother is more apparent
at one period of their lives, become much more like their
father at another period. In accounting for this it has
been stated that these phenomena depend upon the deep-
lying potentialities of the family stock, which lie hidden
.and dormant in every individual until developed by either
" the shock of the constitutional changes which take place
naturally at particular epochs of life — the intimate bodily
•changes that are induced by the disturbing effects of such

14

abnormal events as fevers or other illnesses, or by the outer
stimuli of particular circumstances of life."1

The inheritance of the complexion and quality of the
skin is so commonly observed that I need not do more
than mention the fact; while, of all that concerns the
shape and size of the body, I shall only refer to obesity or
corpulence, which is without doubt very frequently hereditary,
and the predisposition to it may be derived from either
parent. Youth, middle, and old age are, perhaps, equally
subject to this condition, but .it occurs more frequently in.
females than in males, and in the single oftener than in the
married. That nations are prone to it as well as families
may be seen in the contrast between, for example, the Dutch
and the Americans. As Ribot says : — " So truly is obesity
the result of an organic predisposition, that it has often been
known to make its appearance amid privations, and under
all the disadvantages of hard labour and poverty."

The internal, like the external, structure of the body is
alike subject to the influence of heredity, and in the great
work of Dr. Prosper Lucas may be found many striking,
examples. Thus, in the osseous, digestive, circulatory,*
muscular, and nervous systems, — in the fluids as well as in,T
the solids of the body, the laws of heredity are as rigidly ,
obeyed as in the external configuration. Ray, and Cuvier
after him, went so far as to say that there is even a greater
similarity in the internal than in the external structure of"
the body. Take, for example, the distribution of the external
veins in the hands of two individuals, and they will be found
to differ considerably: whereas, the internal veins in two
different individuals will be found to closely correspond.
The shape, size, and anomalies of the bones are also
1 Dr. Maudsley.

i5

inherited, and their relative proportions preserved; whilst in
some families the heart and great blood-vessels are found
naturally large, in others comparatively small. The relative
size of the brain, and other peculiarities of the nervous
system, are indisputably transmitted from parents to children;
and that certain families are characterised by a plethora or
paucity of blood, or of bile, is a matter too well known to
require further consideration.

What physicians denominate as idiosyncrasies are very
frequently, if not invariably, inherited ; and that what have
been termed the "subordinate" in contradistinction to the
" dominant characteristics " are hereditarily transmissible is
proved by the well-known facts as to fecundity and longevity
which often characterise families for many generations. Just
as some families are distinguished by the hereditary trans-
mission of longevity, so may others be characterised by
short duration of life, as strikingly exemplified in one
generation after another. There are other cases of a still
more interesting character where, from one generation to
another, the members of certain families seldom, if ever,
survive after a certain age. To this class of cases belong
also the many instances of premature bodily and mental
decay to which some families are subject as the result of
heredity — the exemption, or comparative immunity shared
by other families as to the influence of certain contagious
diseases, and the increased susceptibility of others : and
that muscular strength and special skill in certain physical
exercises are hereditarily transmitted is a fact as well known
now as in early times ; also lisping, stammering, shrillness
and gruffness of the voice, nasal intonation, and loquacity.

That acquired modifications are also transmissible there
can be no doubt ; and amongst these, perhaps, none more

i6

certainly than peculiarities of habit— habit being understood
to imply "an acquired disposition." Curiously enough,
experience seems to warrant the belief that the less important
and remarkable the habit, the more likely is it to become
hereditary and persistent ; and of the many phenomena of
heredity few are more curious and interesting than those
which illustrate the transmissibility of individual peculiarities
and eccentricities, however otherwise comparatively trivial in
themselves, as frequently evidenced in many families. There
are very numerous records of such cases, and, indeed, it is
more than probable that close observation would enable us
to detect evidence of such phenomena, varying of course in
degree, much more frequently than is generally supposed.

The majority of people are undoubtedly right-handed,
but some are naturally left-handed ; and it is interesting,
and sometimes amusing, to observe the many and various
theories propounded to account for this curious physiological
fact. One author goes so far as to suggest that left-handed-
ness is a peculiarity akin to monstrosity, whilst another
believes that those who are left-handed must be generally
eccentric in every respect ! I have no intention, however,
of entering into any discussion regarding these speculations,
and shall now only contend, as I am prepared to prove, that
in a very large proportion of cases of left-handedness, there
is a potential and indisputable element of heredity.

From the foregoing facts, to which many additions might
be made, it will be seen that the grand law of heredity is
intimately and inseparably associated with every anatomical
conformation, and with every physiological function and
process in the human, as, indeed, in the entire animal
economy — not only general characteristics, but "the varieties,
.and the minutest peculiarities of the individual, in structure,

17

composition, and properties," being alike subject to heredi-
tary transmission.

Congenital malformations, or native peculiarities in the
human subject (and equally, indeed, in the lower animals)/
manifest the strong tendency to variability which exists in
nature, and the infinity of means which she makes use of in
order to accomplish the same ends. Slight deviations from
the normal type are distinguished as varieties, while those of
a more striking character are known as lusus natures, and
those in which the deviation is so marked as to seem out of
the course of nature altogether are regarded as monstrosities.
These three degrees of deviation have been classified by
Buffon as excesses, deficiencies, and misplacements ; and
to these Blumenbach has added a fourth, unnatural forma-
tions. No hard and fast line of demarcation, can, however,
be laid down, as the four divisions are frequently combined
in one example, and each may in some degree co-exist with
each — the grades and kinds of abnormal variations being
simply infinite. Different varieties may not only occur in
the same individual, but in different members of the same
family ; and both excess and deficiency may co-exist in one
subject, as in having too many fingers on .one hand, and too
few on the other. One part may be over-developed, whilst
another in the same subject is deficient, as in cases where
supernumerary fingers are associated with hare-lip or spina
bifida ; and, in the same family, one member may have
supernumerary fingers and toes, and another have a deficiency
of one or both. Nothing, however, can be more certain
than that these developmental freaks, whether of the nature
of redundancy or deficiency, are transmissible, and frequently
perpetuated through several generations, and therefore, as
Ribot says, of great interest as shewing that " the individual

i8

type is subject to the law of heredity no less than the
specific type."

It must, however, be remembered that an exact likeness,
(either physical, mental, or moral, is never transmitted by
^inheritance ; neither an exact likeness of either parent, nor
Van exact composite of both. All breeders of stock know
very well that if they wish to develop and perpetuate certain
qualities in the offspring, they must exercise the greatest
care in the selection of the parents ; and human beings,
however well-informed, are far too prone to forget that
similar laws are still more applicable to themselves. The
fact is, that as the law of inheritance of like qualities in the
lower animals manifests itself in simpler and less complex
channels than in the human species ; so, also, it is less largely
modified in the former than in the latter by laws of variation.
As Dr. Maudsley says : — " There is always a principle of
variation at work in breeding, contesting the ground, as it
were, with a principle of heredity, the effects of which are so
great sometimes that resemblances are hidden or overborne
entirely. Now, as the human body is the most complex
organic substance in the world — ' the most compounded mass
in nature,' as Bacon calls it — it affords infinite scope for
modifications, neutralisations, and variations of qualities ;
and the reasons are obvious why we cannot predict results.
Countless variations may occur in each case. . . . Most
of these variations die with the individual ; but some of them,
meeting with fit surroundings, and being fostered thereby,
are propagated from one generation to another, and become
fixed qualities of the family stock. For the qualities of the
stock are deeper and more stable than those of the individual,
and the qualities of the species deeper and more stable than
those of the family. The law of heredity is most evident in

19

the preservation of the character of the species, the law of
variation in the determination of individual characters."

" According to the Darwinian theory," says Balfour, in his
admirable Comparative Embryology, " there are two guiding
— and, in a sense, antagonistic — principles which have
rendered possible the present order of the organic world.
These are known as the laws of heredity and variation. The
first of these laws asserts that the characters of an organism,
at all stages of its existence, are reproduced in its descendants
at corresponding stages. The second of these laws asserts
that offspring never exactly resemble their parents. By the
common action of these two principles, continuation from a
parent type becomes a possibility, since every acquired
variation has a tendency to be inherited." The so-called
theory of evolution is the sublimest philosophical conception
of the present century, and has received its grandest
expression in the elaborate works of Mr. Darwin, in which
he has brought it to bear upon the highest problems which
can engage the attention of mankind. Succeeding the
metaphysical system of Hegel, it has itself been further
extended by the more recent efforts of Mr. Herbert Spencer,
Professors Huxley, Tyndall, and others ; but with the name
of Darwin will ever be associated the completion of the
doctrine of the great organic revolution which may be said
to have been originated by the illustrious Lamarck. As
heredity is inseparable from evolution, I may here briefly
glance at the salient points of the theory, as propounded by
Darwin himself.

The theory of evolution as affecting biology asserts that
" all the species of living beings, both animal and vegetable,
have not been originally created as we see them, but are
derived from ancestors of lower and simpler organisation

20

than themselves, by a process of descent with gradual
modification ; that all species, however different they may
be now, are descended from the same or perfectly similar
ancestors, which, like the simplest living beings now known
to exist, were minute gelatinous masses, without organisation
or structure." In his work on " The Origin of Species,"
Darwin says that, in his belief, " animals are descended
from at least only four or five progenitors, and plants from
an equal or lesser number. Analogy would lead me one
step further — namely, to the belief that all animals and
plants have descended from some one prototype."

The theory has been thus fairly stated in outline : — " All
organisms are more or less variable; no two leaves in a
forest are exactly alike, and the differences are often great
enough to be quite conspicuous, as in the familiar case of
human faces. At the same time these variations tend to
become hereditary. Now, if any variation is such as to give
its owner any advantage over other individuals of the same
species, the owner of such a 'favourable variation' will
be more likely than less favoured individuals to win a place
in the struggle of existence, and to leave offspring. These
offspring will tend to inherit the favourable variation that
caused their parent to survive, and the same competition
will go on among them. Those which possess the favour-
able variation in the highest degree will again survive, and
the improvement will go on progressing and accumulating
through generations. This preservation of favourable
variation Darwin calls ' Natural Selection.' "

The influence of cultivation and domestication in the
production of changes, and the difficulty in distinguishing
between variations and species, are fully estimated and
minutely considered by Darwin in the elaboration of his

21

theory. He draws an analogy between the artificial selection
employed by breeders in the production and perpetuation
of new breeds or varieties, and natural selection, or that
process which all organised beings must undergo, whether
animal or vegetable, in the "struggle for existence " against
not only those other creatures which prey upon them, but
to a still greater extent against those which are similarly
nourished as themselves. "The struggle for existence
inevitably follows from the high geometrical ratio of increase
which is common to all organic beings." It is impossible
that all should live. "A grain in the balance may determine
which individual shall live, and which die — which variety or
species shall increase in number, and which shall decrease,
and finally become extinct." Thus it follows that, as only a
fractional part of those which are born shall survive and
produce descendants, the weaker, or those least fitted to
conquer in the struggle for existence, must succumb and
perish, whilst the stronger, more capable of overcoming by
reason of their more favourable organisation, alone survive :
and so the struggle for existence results in the " survival of
the fittest."

Slight variations may be perpetuated, and those creatures
which, owing to natural advantages, possess greater powers
of attack and defence, and which are more adapted for the
acquisition of nourishment, naturally overcome those less
favoured, and eventually displace them. That striking
modifications may be produced and perpetuated in the
careful cultivation of plants is undeniable, and Darwin asks :
" Can it, then, be thought improbable, seeing that variations
useful to man have undoubtedly occurred, that other
varieties useful in some way to each being in the great and
complex battle of life should occur in the course of many

22

successive generations ? If such do occur, can we doubt
(remembering that many more individuals are born than can
possibly survive) that individuals having any advantage,
however slight, over others, would have the best chance of
surviving and procreating their kind?" In this way Darwin
supposes " new variations to be continually taking place, but
the greater number of them speedily to become extinct ;
whilst others, becoming perpetuated, and perhaps causing
the extinction of the original forms, again give rise to other
forms, until some of them have so widely diverged that all
traces of their common origin is lost." " As buds give rise
by growth to fresh buds, and these, if vigorous, branch out
and overtop on all sides many a feebler branch ; so by
generation, I believe, it has been with the great Tree of Life,
which fills with its dead and broken branches the crust of
the earth, and covers the surface with its ever-branching and
beautiful ramifications."

It would be foreign to the purpose of these papers to
discuss at any length this grand theory of evolution. But,
independently of all that might be said either in favour of
or against it, it should always be remembered that of all
possible theories of the origin of species, it is that which
is most in harmony with the ordinary facts of experience.
The origin of individual organisms is a matter of scientific
observation; but the origin of species must still be re-
garded as inferential. Bearing in mind, however, that
every living organism has been evolved out of a perfectly
simple cell, in which the microscope shows no vestige .of
structure, it certainly seems more consistent with this fact
that species have been developed by " descent with modi-
fication" from perfectly simple ancestral forms, than to believe
that they have been created all at once just as we see them.

23

We must, therefore, regard heredity and evolution as
inter-dependent and inseparable, as without heredity every
change of modification of any kind could only exist tran-
sitively, and would inevitably cease with the individual ;
and without evolution heredity could only necessitate the
" monotonous conservation of the same types, fixed once
for all." Life and variation are rendered possible by
evolution and heredity, the former producing modifications
which habit fixes in the individual, and heredity perpetu-
ates in the race. As Ribot says : " These modifications,
as they accumulate, and in course of time, become organic,
make new modifications possible in the succession of
generations. Thus heredity becomes in a manner a crea-
tive power."

/" Heredity in an individual consists of qualities both
'physical and psychical, which may be denominated
(ancestral, parental, and acquired. The latter qualities are
without doubt transmissible, notwithstanding the fact that
in many cases, especially when a race is left to itself, such
deviation of type has, apparently, a tendency to revert to
the normal state. Independently of some exceptional and
reversional cases, it is a well-established fact — proved by
the phenomena of physiological heredity, as detailed in
innumerable instances of the transmissibility of acquired
modifications — that by careful selection breeders are
enabled not only to fix but to perpetuate certain physical
characters. When those animals possessing such acquired
modifications are " left to themselves," there is undoubtedly
a tendency to revert to the primitive type ; but as the art
of the breeder fixes them in the lower animals, so can they
be perpetuated in man under certain definite conditions.
" Thus there is established in the individual, between the

24

heredity of natural characters and that of acquired charac-
ters, a conflict, in which nature must win, if art does not
counteract it." x

Thus far we see that the study of heredity teaches us
concerning the inheritance of like qualities — the dormancy
or suspension of qualities which may become manifest on
a particular occasion in the individual life or in subsequent
generations (as evidenced by the fact that children whose
likeness to their mothers is apparent at one period of their
lives, at another will become much more like their fathers),
and the combination to produce certain qualities or varia-
tions. I shall now briefly inquire into the so-called laws
of heredity — empirical, no doubt, but applicable to the
many oddities, exceptions, and contradictory opinions
which complicate the question when we venture to proceed
from theory to individual facts, and which may all be
brought within the compass of the following few formu-
laries : —

I. — Direct Heredity.

II. — Reversional Heredity, or Atavism.

III. — Collateral, or Indirect Heredity.

IV.— The Heredity of Influence.

V. — Specialised or Initial Heredity.

De Quatrefages says : " Clearly the mathematical law of
heredity would be for the parent creature to reproduce
itself in its progeny. And perhaps this law, absolute though
it be, is to be found underlying all natural phenomena ; but
in every case it is marked by accessory circumstances — by
the conditions amid which heredity acts. But it does not
only rest on theoretical considerations — it rests also on facts.
Although subject to profound and continual disturbance,
1 Ribot.

25

still, if we note all the phenomena which show in individuals
a tendency to obey the mathematical law, heredity is found
to realise in the aggregate of each species the result which
it fails to realise in isolated individuals. To use a figurative
expression, the true meaning of which cannot fail to be
apprehended, while it cannot be verified in the whole, it
may be in detail."

Direct Heredity consists in the transmission of paternal 1
and maternal qualities to the children. This form presents "
two aspects —

I. — A child may resemble both its parents equally, as
regards both physical and moral characters. This is com-
paratively rare, as it would be a manifest realisation of the
ideal law.

II. — A child, whilst resembling both parents, may
resemble one of them peculiarly. This second class admits
of two sub-divisions — viz., (a) the likeness may be in the
same sex — from father to son, from mother to daughter;
(b) more frequently the heredity occurs between different
sexes — from father to daughter, from mother to son.

(i) Perfect equilibrium is only compatible with " perfect
equality of action — a perfect correspondence beween the
physical and mental constitution of the parents," which
are not to be found ; and thus, among the higher animals
at any rate, the realisation of the ideal law is unattainable,
owing to the absence of the necessary conditions. That
there is always a preponderance of one of the parents is the
one clear result arising out of the conflict of opinions. As
Ribot says : " In the case of direct heredity the child is
always more specially like either the father or the mother."
The preponderance, moreover, is never exclusive, but always
bi-lateral. " Although the influence of one of the parents

26

on the child may seem abolished, it is never annihilated,"
and thus "the law of equality of action is as far as possible
realised." To sum up — a child, in the case of direct
heredity, derives its qualities from both parents, but there is
always a preponderance of one of them.

(2) The preponderance may be either direct or diagonal
— viz., direct when the son resembles the father, and the
daughter the mother ; diagonal when the son resembles the
mother, and the daughter the father. The law of diagonal
heredity has comparatively few exceptions, and may be
explained by a cycle of heredity, thus : by examining
several generations, it is found to pass from the grandfather
to the mother, and from the mother to the son ; or from
the grandmother to the father, and from the father to the
daughter, then back again from whence it started. Cross or
diagonal heredity is still more common when one of the
parents presents any anomaly or deformity, thus : organic
imperfections (as curved spinej lameness, rickets, sex-digitism,
deaf-muteness, mycrophthalmy, etc.) pass from father to
daughter, and from mother to son. Gall cites a case of twins
of opposite sexes — the boy like the mother, very stupid ; the
girl like the father, very intelligent.

(3) The preponderance of one parent is sometimes shown
in the children of the same sex, but instances of this kind
are not so numerous as in cross heredity. Edward Lambert,
"the Human Porcupine," transmitted his peculiarity only
to the males of his family. Daltonism, or colour-blindness,
is generally more frequent in men than in women, yet it has
been transmitted through five generations, to twelve persons,
all women ! " Constitution, temperament, fecundity, lon-
gevity, idiosyncrasies, and anomalies of every kind, pass as
often from father to son as from mother to daughter."1

1 Ribot.

27

Reversional Heredity, or Atavism^ occurs when a child
resembles its grandparents or earlier ancestors, and is a very
influential law. The grandson very frequently resembles
his grandfather, and the grand- daughter her grandmother.
Lucas thus defines it : " Atavism is a term used to denote
cases in which a child, instead of resembling his immediate
parents, resembles one of his grandparents, or still remoter
ancestor, or even some distant member of a collateral
branch of the family — a circumstance which must be
attributed to the descent of all its members from a common
ancestor." It is also referred to by Aristotle, Galen, and
-Pliny. Montaigne says : " Is it not marvellous that this
drop of seed from which we are produced should bear the
impression not only of the bodily form, but even of the
thoughts and inclinations of our fathers ? Where does this
drop of water keep this infinite number of forms? And
how does it bear these likenesses through a process so hap-
hazard and so irregular that the great-grandson shall resemble
the great-grandfather, the nephew the uncle ?" Atavism has
shown itself in the silk-worm after a hundred generations,
and is beautifully exemplified in the vegetable kingdom, as
shown by Dr. Broca. Reversional heredity is often mani-
fested in insanity. Thus, an insane father may have clever
and distinguished sons, probably geniuses, yet the offspring
of these may manifest insanity at any time, even suddenly.
Character, talents, aptitudes, and passions, afford many
striking examples of atavism.

Indirect Heredity is in reality only a modification of

atavism, differing from it only in appearance. It occurs

r when a child resembles in its physical, mental, and moral

I character, an uncle or aunt, or some other relative out of

the direct line of descent. Some have denied that this

28

form exists, but that the influence of heredity manifests
itself frequently under such circumstances is proved by
innumerable facts as to resemblances of face, inclinations,
passions, characters, deformity, and disease, between uncle
and nephew, aunt and niece, grand-uncle and grand-nephew,
and even amid the ramifications of distant cousinship.
Ribot gives many instances in illustration of this law.

The Heredity of Influence, or pre-marital heredity, is seen
when the child of a second or third marriage resembles the
husband in a previous marriage. Although facts are
forthcoming as to such an influence affecting " the lower and
even the higher animals," yet so far as man is concerned,
the instances of this are very few, if they occur at all. This
form is, moreover, in an unnatural order, and presents no
real analogy to either direct, reversional, or indirect heredity,
as it would necessitate a child "resembling a person who
has nothing in common with him, save that the person was
once its mother's husband."

Specialised, or Initial Heredity. — This is a form of heredity
of considerable importance, although not included in the
formularies given by Ribot. It depends upon the temporary
mood or condition, good or bad, fortunate or unfortunate,
of parents when they became such. " A good initial
heredity," says a writer, "may produce virtue in the
descendants by predisposition merely from a temporarily
ennobled nature, although there was in general vice in the
parents, and so a bad direct heredity. If you are in a lofty
mood Providence is on your side ; but, when a drunkard,
on the one hand, or when, on the other, a man generally
temperate, but in a temporary debauch, places himself
under the power of this law of heredity, the specific or
initial principle acts just as surely to produce an inheritance

29

of evil as it does in the opposite case to produce an
inheritance of good."

Such are the formularies which experience has shown
to include most of the phenomena of heredity ; and they
may be regarded as so many fragments of a single law, of
which we are sensible, but which we cannot rightly under-
stand. The empiric formularies already referred to may
be further reduced to mediate and immediate heredity, and
thus, instead of regarding heredity as from one generation
to another, we may regard it as embracing a much larger
cycle. That heredity thus embraces cycles is amply shown
amongst the lower animals, although no instances of
alternate generation are known amongst vertebrates.

With regard to cases of reversional heredity, when the
grandson resembles the grandfather, the grandnephew the
granduncle, the intermediate stages being totally unlike
either, the phenomena may be explained by the fact that
these resemblances have been preserved in the latent state
by the intermediate generations, and then what appears to
be mediate heredity is really immediate. Latent characters
are "those secondary characters of each sex which lie
dormant in the opposite sex, ready to be evolved under
peculiar circumstances." z The law of heredity is in latent,
albeit not in patent, action. This latency or dormancy of
ancestral qualities, that afterwards wakes again to open
activity, is proof that the effect of the union of two persons
may be to hold special qualities of each other in a sort of
neutralisation or check, released from which they show
themselves again, just as an element in a chemical compound
exhibits its own properties again as soon as it is free.2

2Dr. Maudsley.

3°

Darwin says we are obliged to admit that certain characters,,
aptitudes, and instincts may remain in the latent state in an
individual, while yet we are unable to find any trace of their
presence ; thus may the above resemblances be explained.
These latent characteristics of heredity are peculiarly
applicable to what may be termed "heredity occurring at
corresponding periods," which may be explained on the
hypothesis of latent characteristics contained in the
individual, in the germ state, and which come to light only
under definite conditions, at some particular point of his
development, and this particular moment corresponding with
a similar moment in the progenitor.

Ribot thus graphically says: — "Still it is evident that
these formulas cannot pretend to give a complete explanation
of a fact so abstruse and so complex as hereditary trans-
mission. Our only purpose is to show that the term is
taken in too narrow a sense when it is restricted to two
generations, and that the facts seem less strange so soon as
we grasp them as a whole. We desired also to exhibit
the wonderful tenacity of heredity. Its law is absolute
transmission ; and, in spite of all the obstacles which tend
to weaken or destroy it, it struggles on without truce or
pause, losing much of its strength as it advances, dissipating
itself, so to speak, so as to appear no longer to exist, and
yet, when we see the same characters reappear, sometimes
after a hundred generations, here is, indeed, matter for
reflection. It may be said that heredity verifies in its own
way the axiom — Nothing is lost. With its character of
unconquerable firmness, of obstinate persistency, it appears
to us as one of those many inflexible bonds by which
omnipotent nature imprisons us in necessity."

31

Having thus far briefly considered heredity in its physio-
logical aspect, I now purpose to glance at its psychological
bearings and influence, and shall first premise that between
physiology and psychology there exists not only an intimate
correlation, but an exact parallelism. The brain is the
organ of the mind, and thought is but the result of brain-
action ; the brain as regards its size, structure, and qualities
is hereditarily transmissible ; therefore, we are warranted
in asserting that every mental or intellectual state is con-
ditioned by a pre-existing physiological state, and that
psychological heredity has its source in physiological
heredity. That this is so is proved by the fact that the
nervous system is the physical condition and antecedent of
those phenomena denominated mental and moral ; and that
their interaction and interdependence is such that every
variation in the one necessitates a corresponding variation
in the other: in other words, between the phenomena,
arranged into two groups, as physiological and psychological,
there are intimate relations, whether of "invariable co-
existence or of invariable succession." The one set we
call physiological, when we regard them through the senses and
from without ; the other psychological, when we regard them
through the consciousness and from within. Just as it
would be impossible to think without a brain, so every
mental effort or condition necessitates a corresponding
state of the nervous system, and every state of the nervous
system re-acts proportionately on the great nerve-centres.

Dr. Carpenter says : " Every kind of activity peculiar to
a living body involves a change of structure : and the
formation of the newly-generated tissue receives such an
influence from the conditions under which it originates, that
all its subsequent activity displays the impress. Hereditary

32

transmission of psychical character presents itself under
circumstances that entirely forbid our attributing it to any
agency that can operate subsequently to birth, and which
it would seem impossible to a.ccount for on any other
hypothesis than that the formative capacity of the germ
determines the subsequent development of the brain, as
of other parts of the body, and (through this) its mode of
activity, in accordance with the influences under which
that germ was first impregnated. And thus what we speak
of as the * original constitution ' of each individual is in
great part (if not entirely) determined by the conditions,
dynamical and material, of the parent organisms." When
alluding to the physiological aspect of heredity, I traced
its origin to the fusion of two simple cells, in which were
enshrined all its mysteries. But how manifold do these
mysteries appear, when, in tracing the source of its psycho-
logical aspect, we find it emanating from the same cells.
Not only the characteristic physical structure in its every
detail, but the mental and moral nature and character are
evolved in and transmitted by the fusion of these two
infinitesimal cells ! Here is, indeed, a mystery : that by
this simple, but occult process, is evolved and transmitted
not only the physical, intellectual, and moral likeness of the
parents, but of their ancestors, modified not only by the
natural tendency to variation which is developed in every
child, but by the actual physical and mental condition
of the parents at the time of procreation.

Science, as before remarked, can only record and interpret
phenomena and experience ; and although the facts of
heredity are indisputable, the ultimate causes remain as
inscrutable as ever. She has, therefore, grouped certain
phenomena under the name physiological, and others under

33

the name psychological, but in doing so she has been-
actuated more by a desire to facilitate the study of the
phenomena which the terms respectively represent, than from
any intention of erecting a barrier between them ; for who
can define where physiology ends and pyschology commences?
Like all other groups of natural laws, physiology and
psychology are simply terms used to denote the groupings
of certain phenomena, which experience has enabled us to
perceive are reducible to law ; but to deny the interaction
and interdependence of all natural phenomena would be
simply absurd, and a violation of that unity which the
greatest and most cultured minds have ever observed in
Nature. Physiology and psychology I therefore regard as
representing simply different aspects of man's individuality ;
and, as in the oVie, so also in the other, the facts of which
they consist are those with which Science concerns herself in
the light of human experience. Beyond phenomena and
experience, she can only concern herself with hypothesis ;
and this latter mode of inquiry is unavoidable when we seek
for knowledge of causes ; for though " science begins with
the investigation of laws, it is perfected only in the deter-
mination of causes" — secondary and immediate from
necessity, and involving merely " invariable antecedents."

The respective phenomena of physiology and psychology
may be grouped into two sets — viz., the first external and
unconscious, the second internal and conscious ; but it
must be conceded that there is an intimate correlation
between the two, inasmuch as every mental condition
implies and necessitates an antecedent physical condition,,
as, for example, in the case of pain, as cited by Ribot,
where " this sum of states of consciousness is accompanied
by certain states of the organism, motion, play of the

34

physiognomy, states of the viscera, and vice versa" The
physiological phenomena, therefore, may be regarded as
concerning unconsciousness ; but between the two there is
an intimate interaction, interdependence, and correlation-
ship, whether of " invariable co-existence," or of "invariable
succession." The psychological phenomena associated with
automatism are a further proof of the argument : thus, with
regard to the spinal cord, which is the nerve-centre presiding
over reflex action, the reflex phenomena are not only auto-
matic, but unconscious and co-ordinated : so also the
medulla oblongata, a still higher centre, which governs such
phenomena as respiration, deglutition, coughing, sneezing,
yawning, and the like, and for the most part uncon-
sciously. Proceeding still higher, the cerebellum, whose
office it is to preside over the co-ordination of the muscular
contractions which produce the various movements of the
body, acts quite unconsciously : and lastly, the brain proper
itself, which also is capable of acting unconsciously, as is
well attested by the interesting phenomena of somnambu-
lism, ecstasy, catalepsy, etc., which have been grouped
together under the term "unconscious cerebration." Analy-
sing still further, we find that instinct, memory, habits, the
emotions, all have their origin in the " dim region of the
unconscious," and, further still, that "every mode of intel-
ligence has its unconscious form," even to the grandest
efforts of the imagination. " As for the will," says Ribot,
" it derives ultimately from character, and the root of
character is in the unconscious."

I must here content myself with the simple enumeration
of these facts, as arguments, not to say proofs, would take
a volume for their consideration. What I am anxious to
•convey is that physiological and psychological phenomena,

35

instead of being distinct and different, are really so inti-
mately correlated, and interdependent that the higher may
be regarded as simply a development of the lower, and
that while " there is no mode of mental activity which may
not be produced under its unconscious form," for every
conscious form' there is a corresponding unconscious one.
" The phenomena which constitute physical and mental life,
taken in their totality, seem to form a continuous series of
such a nature that at the one extremity of the series all is
unconscious and purely physiological, and at the other end
all is conscious and purely psychological ; and that the
transition from the one extreme to the other is performed
by insensible gradations, whether it be that the unconscious
rises to the conscious, or that the conscious returns to
unconsciousness. The purely physiological phenomena
appear to be reduced in the last analysis to motion^ and
purely psychological phenomena to sensation.'1

From what I have thus far stated it will be seen that the
development of the mind depends entirely upon the
development of the brain, and that psychological heredity
has its source -and antecedent in physiological heredity.
That this is so will appear all the more evident when we
consider that all that we have and are, as individuals con-
stituted for the performance of certain functions, we owe
to heredity, with the exception of the developing influences
of our " environment " through life, and the educational
processes to which we have been subjected. For if mental
development is ever, and in all cases, subject to organic
conditions, as it undoubtedly is ; and if, with the organism,
the nervous diathesis and structure of the parents are
inherited — their mental capacities and peculiarities must
1 Ribot.

36

be similarly transmitted. Just, in fact, as the qualities of
a plant are transmitted in its seed, so, not only the physical,
but the mental characteristics of the organism are trans-
mitted from parents to their children. Moreover, the brain,
which I have denominated the organ of mind, is, as Dr.
Mortimer Granville says, " composed of nerve cells and
fibres, the latter serving to communicate, and the former
being endowed with the power of receiving and recording
the impressions produced by external objects through the
senses, together with such conceptions of impression as are-
evolved in the course of the operations of thought. No
intellectual function is performed, or sensation experienced
or imagined — in short, nothing takes place in the mind, or
within the range of the perceptive faculties — without a
physical change in the minute structure or organism of the
brain, and the physical changes so produced are the records
which form the bases of memory. . . . More than this,
as family likeness is perpetuated from parent to child, the
brain, with its characteristic properties, will be reproduced,
at least, so far as to give an inherited bias to the mind of
posterity. It is in this way mental constitutions are trans-
mitted, and tendencies to the commission of crime or the
practice of virtues, special powers of work or particular in-
competencies and neuroses are transmitted also." We thus
see that the embryonic vesicle contains not only the forma-
tive capacity of reproducing the physiological likeness of the
parents, but the potentiality of developing their modes of
thought and action — their character, their powers of
reasoning, their intelligence.

I shall now pass briefly in review those psychological
phenomena1 which are subject to heredity, and which, in

1 Summarised mainly from Ribot.

37

fact, constitute the psychological life of man as contrasted
with his purely organic or physiological functions. If we
are to accept Mr. Herbert Spencer's dictum that " No
thought, no feeling, is ever manifested save as the result of
a physical force," it naturally follows that without a nervous
system no psychological act or function could be performed.
At all events, it will be well to remember that the brain is
the organ of the mind, and thought its function ; that the
physiological phenomena of heredity are conditioned by
unconsciousness, and the psychological by consciousness,
and that without physical organisation there is no con-
sciousness : so that whilst we admit, as Smee says, that
" the human mind cannot understand how a material
organisation may produce, or be associated with, conscious-
ness, so we are compelled to declare that consciousness is
not manifested without a material mechanism."

Passing towards the conscious from the unconscious, I
proceed to notice the heredity of instincts, which I assume
to be indentical with intelligence, save in degree. Instinct
has been defined by Hartmann as "an act conformed to
an end, but without consciousness of that end." Ribot
says : " Instinct is intended to signify the automatic, almost
mechanical, and probably unconscious action of animals,
in pursuance of an object determined by their organisation
and specific characters." And lastly, Darwin says : " An
action which we ourselves should require experience to
enable us to perform, when performed by an animal, more
especially by a very young one, without any experience,
and when performed by many individuals in the same way
without their knowing for what purpose it is performed, is
usually said to be instinctive." However unsatisfactory
these definitions may be as such, they each manifest the

distinction between instinct and all other psychological
phenomena, and if we remember that instincts appear as
perfectly developed in those animals possessing them from
the moment of their birth, whereas intelligence represents
the aggregate of successive experiences ; that the one is
almost immutable and stationary, whilst the other is variable
and progressive — we shall at any rate be able to distinguish
between the two sets of phenomena. Beyond all doubt,
however, instincts, however defined, are hereditarily trans-
missible, as the psychical as well as the physical nature are
unquestionably transmitted from parents to their children.
As surely as the entire range of animal life up to man
himself is possessed of, and actuated by, instincts, so surely
is this immense range subjected to the laws of heredity,
and this fact is so self-evident as to be universally recognised
and admitted. I have just said that instincts are almost
immutable, but they are not quite invariable, as the action
of external circumstances and domestication tend to modify
them to some extent ; and, as showing the potency of
heredity, even these acquired modifications are undoubtedly
transmitted, of which fact I might easily quote many
instances. It is important to remember, however, that there is
a great difference between the heredity of natural and that
of acquired instincts ; for whilst that of the natural instincts
admits of no exception, that of the modifications must
have become persistent, and assimilated by the organism —
in a word, automatic, before they are inherited.

In the light of the evolutional theory " heredity is one of
the essential factors of psychological development ; and so
mighty and supreme is its influence that it not only preserves
instincts, but also creates them." In this light instinct is to
be regarded as " an unconscious form of intelligence deter-

39

mined by the organisation :" and this latter fact is accounted
for by the intimacy of relationship existing between the
physiological and the psychological constitution of every
animal. Whether instinct results from organisation exclusively
is not so well established as the fact that it depends on
organisation ; for the former concerns that " mysterious
transition from the purely organic to the mental life by
means of reflex action, which is principally physiological, and
of instinct, which is principally psychological " — a transition
so subtle and indefinable that we can neither say where
physiology ends and psychology begins ; nor even imagine
how purely physical life evolves itself into mental life. As
sharing the alliance between instinct and intelligence we
have only to remember that, in addition to the conscious
action of the mind, there is also an unconscious action of
far wider range, and that it is possible that the phenomena
of instinct, sensation, perception, memory, etc., are alternately
conscious and unconscious. The phenomena of somnam-
bulism are well known, during which state the somnambulist
will carefully perform any acts which are habitual to him,
albeit instinctively and unconsciously. The phenomena of
habit, also, resembling instinct so closely, manifest similarly
the transformation of intelligence into instinct. The
character of innateness generally associated with instinct, does
not constitute an absolute distinction between instinct and
intelligence if we do not fail to recollect that many instincts
are acquired, and that, according to the evolutional theory,
all instincts are only hereditary habits. "Although," as
Ribot says, " intelligence is, as a rule, conscious, it may also
become unconscious and automatic, without losing its
identity. Neither is instinct always so blind — so mechanical
as is supposed — for at times it is at fault. . . . It is

40

difficult to believe that the loftier instincts of the higher
animals are not accompanied by at least a confused con-
sciousness. There is, therefore, no absolute distinction
between instinct and intelligence ; there is not a single
characteristic which, seriously considered, remains the ex-
clusive property of either. The contrast established between
instinctive acts and intellectual acts is, nevertheless, perfectly
true, but only when we compare the extremes. As instinct
rises it approaches intelligence ; as intelligence descends it
approaches instinct. This must not be forgotten ; and while
differences are borne in mind, the resemblances also must
be noted."

As to the origin of instincts the Darwinian theory accounts
for them, as it accounts for the formation and disappearance
of species, by spontaneous variations, the struggle for life,
natural selection, time, and heredity ; regarding instincts, as
they now exist, as very complex, and formed by the gradual
accumulations of the two latter factors. As Darwin has
studied principally the physiological phenomena, so Mr.
Herbert Spencer has devoted himself to the psychological
aspect of the question, and seeks to describe the evolutional
process which has deduced complex from simple instincts by
heredity and selection. Assuming the unity of composition
of psychological phenomena, he regards instinct as repre-
senting one of the first stages in the ascending evolution of
mind. In the faculties of instinct, memory, reason, etc., he
sees only " a convenient way of grouping and naming phe-
nomena, but no real difference. These phenomena form a
series in which there are only insensible transitions from class
to class. In this ascending series instinct occupies an inter-
mediate place between reflex action and memory ; instinct
may be regarded as a sort of organised memory, and memory
as a sort of nascent instinct."

This theory of the origin of instincts is inseparably related
to the origin of species, and although Darwin has elaborated
his grand scientific hypothesis with the utmost skill and
ingenuity, Science cannot yet be said to have solved the
question as to the origin of species, and until she has done
so, if she ever does, opinions will differ as to whether
instincts should be regarded as a sum of hereditary habits.
"Should Darwin's doctrine be confirmed," says Ribot, "it
must then be admitted that all instincts have been acquired,
and that what is now fixed was at first variable ; that all
stability comes from heredity, which conserves and accumu-
lates ; and that, in the formation of instincts, heredity is
supreme." It is still, however, impossible to say whether an
instinct is the result of hereditary habit, or "a primitive,
natural, and irreducible fact." There is, indeed, no means
of determining which view is correct.

The sensorial qualities — the modes of sensorial activity,
in a word, the perceptive faculties — are undoubtedly trans-
missible, and therefore subject to heredity. This is un-
questionable so far as concerns not only specific qualities,
but in everything regarding race or variety ; it is, therefore,
only in relation with individuals that any doubt can arise.
Ribot asks the following question : " Is the transmission
of secondary and individual characters governed by the
same heredity which governs the transmission, of the
perceptive faculties, in their essential and fundamental
features?" Facts can alone reply; but I hope to show
that " heredity is usually the rule, even with what is indi-
vidual, anomalous and capricious." A brief consideration
of the special senses will now be necessary, and, as
generally enumerated, these consist of five — viz. : touch,
sight, hearing, smell, and taste — although a sixth, repre-

42

seating a mode of sensation without any special organ,
and described as a vital or internal sense diffused over the
whole body, by means of which we are sensible of what
takes place within us, is now generally recognised. Sen-
sation is said to consist in the mind receiving, through the
medium of the nervous system, and, usually, as the result
of the action of an external cause, a knowledge of certain
qualities or conditions, not of external bodies, but of the
nerves of sense themselves, and these qualities of the nerves
of sense are in all different, the nerve of each sense having
its own peculiar quality. Smell, sight, and hearing depend
for their manifestation on the existence of a special nerve
for each ; whereas taste appears to be a property common
to branches of two nerves, and touch is not confined
to particular parts of the body, of small extent, like the
other senses ; on the contrary, all parts capable of per-
ceiving the presence of the stimulus by ordinary sensation
are, in certain degrees, the seat of this sense; for touch
is simply a modification or exaltation of common sensation
or sensibility. The nerves on which the sense of touch
depends are, therefore, the same as those which confer
ordinary sensation on the different parts of the body.1

Touch may be regarded as the universal, fundamental
sense possessed by all sentient animals, as Mr. Herbert
Spencer 'has ably demonstrated how the other senses, by
evolution and specialization, could have arisen from the
sense of touch. Tactile sensations, and the sensations of
temperature, are alike subject to heredity. Prosper Lucas
says that " parents transmit to their children the most
singular perfections and imperfections of touch. There
are, probably, in the skin, no modes of hyperaesthesia, or
1 Kirkes' Physiology.

43

of anaesthesia, that could form an exception to this rule."
The relative susceptibility and insusceptibility of some
individuals and families to tickling is well-known, and the
numerous idiosyncrasies as to contact with silk, cork,
woollen clothing, etc., need only be mentioned. These
are unquestionably hereditary. The hand itself — the very
organ of touch — is affected by heredity. For as Mr.
Spencer has observed : " Large hands are inherited by
men and women whose ancestors led laborious lives, and
men and women whose descent, for many generations, has
been from those unused to manual labour, commonly have
small hands." A predisposition to left-handedness is also
transmissible, as the writer can prove from the following
circumstances connected with his own family. For at least
four generations there has been a strong tendency to left-
handedness in each. Thus, my paternal grandfather, who
was an excellent sportsman and a first-rate marksman, shot
from the left shoulder, as I do myself ! In each of the four
generations, some member, or members of the family,
showed the strongest tendency to left-handedness ; and
during my childhood my left arm was bound up for weeks,
but all to no purpose : Natura non nisi parendo vindtur I
Still more curious is the fact that my sisters' children
manifest the same tendency.

With regard to sight — "the most intellectual of all the
senses" — its varieties depend on mechanical causes, and on
anaesthesia or hyperaesthesia of the nervous apparatus of
vision, and all anomalies are hereditarily transmissible.
Amongst those peculiarities dependent on mechanical causes
may be included strabismus, myopia, and presbyopia : these
are all markedly hereditary. Ribot says : " Anaesthesia of
the nerves of sight is transmissible in all its grades, and in

44

all its forms. It is a well-known fact that the sensibility
of the eye to light is very different in different persons. It
may vary as much as 200 per cent, and, of course, will pass
through all the intermediate degrees. Heredity transmits
these inequalities, from partial to total anaesthesia, or blind-
ness, when the eye, incapable of noting form or colour, has
only an indistinct perception of light. Congenital blindness
may run in families. Blind persons will sometimes beget
blind children. . . . Amaurosis, nyctalopia, and cataract
in the parents may become blindness in the children ; and
such transformations of heredity are not rare in animals."
Daltonism, or colour-blindness, is well-known to be heredi-
tary, and an example is quoted by Darwin, wherein in eight
families, akin to each other, this affection lasted through
five generations, and extended to seventy-two individuals.
Hyperaesthesia of the optic nerve frequently produces, in
some persons, great acuteness of vision, so extraordinary,
indeed, as to be almost regarded as supernatural. Several
examples of this are recorded by Prosper Lucas, in all of
which there was a potent hereditary element. As with all
other specific characters, in every species of animals, heredity
preserves and transmits a visual apparatus of a structure and
optical power peculiar to each ; so that there can alone be
any doubt with regard to individual varieties, but there are
good reasons for believing these also to be transmissible.

Although it would be useless to institute an inquiry as to
which of the senses is the most important, since opinions
would inevitably differ, yet I cannot be far wrong in asserting
that that of hearing is of prime importance, since on it
depends not only the possibility of speech and, therefore,
thought, but it constitutes the foundation of the science of
acoustics, and also of the art of music. Similarly to sight,

45

which, as we have seen, may be most acute, or so weak as
to merge into blindness, so the sense of hearing may include
every gradation from the most sensitive and acute to insen-
sitive or deafness. Opinions seem to differ as to whether
deaf-muteness is transmissible or not; but Dr. Meniere,
whilst admitting, that in some cases, the hereditary element
has been admitted, says : " Nevertheless, these facts must
be held to constitute a rare exception ; habitually deaf-mutes
married to deaf-mutes beget children who hear and speak.
This is, of course, still more the case when the marriage is
a mixed one, that is, when only one of the couple is deaf
and dumb — though in this case there are well-attested cases
of heredity." As Ribot points out : " The returns of the
Deaf and Dumb Institution of London, from its foundation
to the present time, are conclusive in favour of heredity.
Amongst 148 pupils in the Institution at one time there was
one in whose family were five deaf-mutes ; another in whose
family were four. In the families of eleven of the pupils
there were three each, and in the families of nineteen two
each." May not the commonly observed non-inheritance of
deaf-mutism be explained by the fact that when both parents
present the same characteristics, heredity may acquire such
power as to destroy itself? In this way Sedgwick seeks to
account for the fact that two deaf-mute parents often give
birth to children that can hear and speak ; but after all,
these facts go only to show by what "concurrence of
fortuitous circumstances, and accidental causes, nature
produces diversity."

I have taken pains to make it clear that hereditary trans-
mission does not entirely verify the truth of the axiom that
" Like produces like," which would be a realisation of the
unattainable ideal law, but concerns itself specially with the

46

transmission of functional and organic predispositions or
tendencies from the parens to the partus ; and thus, although
the vast majority of characteristics is always inherited, as
facts prove, yet the tendency to variability which exists, cor-
relatively with heredity in every organic being, necessitates
individual differences. This is very clearly stated in the
following quotations from the admirable works of two
French authors, the first of whom, Dr. Moreau, in his
Psychologic Morbide, says: "It shows an incorrect conception
of the law of heredity to look for a return of identical
phenomena in each new generation. There are some who
have refused to subject mental faculties to heredity, because
they would have the character and intelligence of the
descendants exactly the same as those of the progenitors ;
they would have one generation the copy of the other that
went before it — the father and son presenting the spectacle
of one being — having two births, and each time leading the
same life under the same conditions. But it is not in the
identity of functions, or of organic or intellectual facts that
we must seek the application of the law of heredity, but at
the very fountain-head of the organism in its inmost consti-
tution. A family, whose head has died insane or epileptic,
does not of necessity consist of lunatics and epileptics ; but
the children may be idiots, paralytics, or scrofulous. What
the father transmits to the children is not insanity, but a
vicious constitution which will manifest itself under various
forms, in epilepsy, hysteria, scrofula, rickets. Thus it is
that we are to understand hereditary transmission."

So, too, Dr. Morel, in his Traite des Degemrescences, says :.
" We do not mean exclusively by heredity the very complaint
of the parents transmitted to the children, with the identical
symptoms, both physical and moral, observed in the

47

progenitors. By the term heredity we understand the
transmission of organic dispositions from parents to children.
Mad doctors have, perhaps, more frequent occasion than
others for observing this hereditary transmission, as also
the various transformations which are exhibited in the
descendants. They are aware that a simple neuropathic
state of the parents may produce in the children an organic
disposition which will result in mania or melancholy —
nervous affections which, in turn, may give rise to more
serious degeneracy, and terminate in the idiocy or imbecility
of those who form the last links in the chain of hereditary
transmission."

But to return. Deaf-muteness of the parents may be so
metamorphosed in their children as to result in a minimum
of hearing, imperfectly-articulate speech, mental dulness and
weakness, or even idiocy. Many instances of these facts
are given by Menckel, the celebrated anatomist. The main
fact, however, which we have to bear in mind, is that all the
phenomena of hearing, whether of the nature of hyper-
assthetic or peculiarly acute, or of anaesthetic, or that
amounting almost to deafness — with every intermediate
grade — are undoubtedly heritable and transmissible in the
sense which I have explained. Like all other laws, heredity
has its exceptions : thus the comparative infrequency of the
inheritance of deaf-mutism. How these transformations or
metamorphoses occur is beyond the power of science to
say. With regard to deaf-mutism, probably Sedgwick, as is
mentioned before, is right in supposing that the prepotency
of the same characteristics in both parents, in some
mysterious way, neutralises the hereditary element so that
they are not transmitted ; but, be this as it may, heredity is
a law which is always being realised, but never ideally so ;

48

so that whilst always a law, it is always the exception, for
although the heredity of the great majority of the
characteristics is universally acknowledged, the aggregate of
all the characteristics is never realised.

Smell and taste are so nearly related that I shall briefly
consider them together. The first of these senses is much
more acute in some of the lower animals than in man, and
in the latter it is very much a matter of race. Dogs are
generally regarded as valuable on account of their acuteness
of smell, which is certainly hereditary. This peculiarity is
also inherited by all the carnivorous animals, and by
numerous insects. The savage races of men may be said to
be allied to the lower animals by the peculiar acuteness of
smell by which they are distinguished. " In North America
the Indians can follow their enemies or their game by the
scent, and in the Antilles the maroon negroes distinguish by
the scent a white man's trail from a negro's."1 In fact the
whole negro race has this sense extraordinarily developed.
Amongst the white races the sense varies, as the others do,
in point of sensitiveness or olfactory obtuseness, in every
possible degree, and we must all be acquainted with families
in which the sense is most acutely developed, and with
others who are scarcely able to discern one smell from
another. The idiosyncracies frequently associated with the
sense of smell are also very interesting ; but whether in the
lower animals or in man — whether of the nature of degree
or of idiosyncrasy — all the phenomena of the sense of smell,
whether innate or acquired, are preserved and transmitted
by heredity.

As in the case of smell, so with taste ; its varieties, whether
specific or individual, are hereditarily transmissible. Burdach
1 Dictionnaire des Sciences Medicaks.

49

has recorded some interesting facts connected with the
lower animals, and associated with hybridism. Thus he
says : "The swine has a very strong liking for barley; the
wild boar will not touch it, feeding on herbage and leaves.
From a cross between a domestic sow and a wild boar came
young, some of which have an aversion to barley, like the
wild boar, while the others have a taste for it like the
common hog." In the case of man also, many men,
individuals as well as families, have a defective sense of
taste, whilst in the case of others, the sense may be most
sensitive and refined. Some, on the other hand, have an
inherent and marked dislike for certain flavours ; and all
these peculiarities, of whatever grade, are emphatically
hereditary. Many facts might be given in support of this
latter assertion ; also with regard to the transmission of a
positive distaste for certain articles of food, as cheese, an
inherent liking for vegetable, and repugnance for animal food,
or vice versd, etc. I have, however, quoted sufficient facts
to show that "there is such a thing as heredity of the
perceptive faculties, even under the individual form ; " and
that in animals, " the quantity and quality of the perceptive
faculties will be certainly transmitted in their specific form,
and very probably, too, in their individual form ; therefore
heredity is the rule." Whether the highest forms of
intellectual faculties and activities are subject to the law of
heredity, I shall now proceed to consider.

The functions of the cerebral hemispheres are those of the
organs by which the mind (i) perceives those clear and
more impressive sensations which it can retain, and accord-
ing to which it can judge ; (2) performs those acts of will,
each of which requires a deliberate, however quick, deter-
mination ; (3) retains impressions of sensible things, and

reproduces them in subjective sensations and ideas ; (4)
manifests itself in its higher and peculiarly human emotions
and feelings, and in its faculties of judgment, understand-
ing, memory, reflection, induction, and imagination. The
organs, therefore, in and through which the mind acts in all
these operations are the cerebral hemispheres.1 The facul-
ties into which the intellect has long been divided consist of
memory, reason, imagination, conception, and others ; but,
as Professor Bain observes, these are not fundamentally
distinct processes, but merely different applications of the
collective forces of the intelligence. Still, although we may
have no power of memory in radical separation from the
power of reason, or the power of imagination ; and as this
classification of the faculties is, however, otherwise objection-
able, at least familiar, and therefore all the more easily
comprehended, I shall more or less adhere to it in con-
sidering the heredity of intelligence.

Memory consists in the fact that an image once formed in
the brain produces an indelible impression, and may at any
future time recur. In other words, " every sensory impres-
sion which has been once recognised by the perceptive
consciousness is registered in the cerebrum, and may be
reproduced at some subsequent time, although there may be
no consciousness of its existence in the mind during the
whole intermediate period."2 The terminations of the
nerves centrally in the brain are in the grey matter, which is
abundantly supplied by blood-vessels. The nervous tubes
terminate in contact with cells, in which probably the changes
occur which cause the registration of impressions of the
external world, and from which their reappearance occurs to

1 "Kirkes' Physiology."

2 Dr. Carpenter.

constitute the act of memory.1 We may compare these
records to the markings left on the tin-foil by the needle of
the phonograph, or to the characteristic forms in which the
constituent particles of different substances arrange them-
selves in the act of crystallisation. Use whatsoever illustra-
tion we may, the fact to recognise is that some change takes
place, and that a certainly immeasurably minute portion — a
molecule, or a series of molecules — of the brain is cast in a
special form by every act of brain function ; and being so
left, remains the register or record of the impression, the
thought, or the impulse by which it was produced. Two
obvious inferences result from this explanation. First, there
must be a limit to the brain-work possible in a lifetime.
The mass of available molecules may be inconceivably vast,
but it is certain that a period will arrive when every page, so
to say, will be occupied, and then the brain will neither take
in nor give out anything new. Secondly, no thought, or
word, or feeling, can be unimportant or without its influence
on the mind and character, because it leaves an indelible
record behind.2

If we bear in mind that as in the physical, so also in the
mental world, nothing is lost or perishes — nothing that exists
can ever cease to be — we may perceive that the phenomena
of memory are capable of being explained by the great uni-
versal law of indestructibility of force — of the conservation
of energy ; nay, more, the production of the phenomena of
consciousness is shown by the physiological study of percep-
tion to be subject to the law of the transformation of force.
As to what it is that survives our perceptions and ideas, it is
difficult to determine ; but as it may be assumed that " every

1 Smee.

2 Dr. Mortimer Granville.

52

mental act leaves in our physical and mental structure a
tendency to reproduce itself, and that whenever this repro-
duction occurs the tendency is thereby strengthened — so
that a tendency often reproduced becomes almost automatic,"
— the least objectionable term for that which survives our
perceptions and ideas is probably that of residuum^ which
only indicates an unquestionable fact of our mental life.
Nay, more, it may be asserted that " the relation subsisting
between the actual perception and the residuum is the rela-
tion between the conscious and the unconscious," as between
these two worlds there must exist such a correlation that to
each mode of the one a mode of the other corresponds.
As Miiller says : " Forgetfulness means that the idea of a
thing is in equilibrium with other ideas, and recollection that
this idea quits the state of equilibrium, and enters the state
of motion. No idea is lost ; and every operation of the
mind, in virtue of which a latent idea passes to the active
state, is a state of recollection."

Memory may also be regarded as a form of habit, for if in
tracing the evolution of mind we go " from instinct, which
is automatic, to reason, which is so no longer, we may say
that memory is the transition from perfect to imperfect
automatism. If we trace it in the reverse direction, then
memory indicates the moment when what was free and
conscious tends to become unconscious." Indeed, heredity
itself may be said to be a specific memory, being to the
species what memory is to the individual ; and the "heredity
of memory is implied in physiological heredity." Dr.
Maudsley says : " The permanent effects of a particular
virus, such as that of variola or syphilis, in the constitution,
shows that the organic element remembers, for the remainder
of its life, certain modifications it has received. The manner

53

in which a cicatrix in a child's finger grows with the growth
of the body, proves, as has been shown by Paget, that the
organic element of the part does not forget the impression
it has received. What has been said about the different
nervous centres of the body demonstrates the existence of
a memory in the nerve-cells diffused through the heart and
the intestines, in those of the spinal cord, in the cells of the
motor ganglia, and in the cells of the cortical substance of
the cerebral hemispheres." Is memory, then, in its indi-
vidual form hereditary ? The facts in the affirmative are
comparatively few, for obvious reasons, and principally
because the study of mental heredity has hitherto been
sadly neglected. There can, however, be no doubt that the
heredity of the memory is implied in physiological heredity,
as what is true of part must also be true of the whole. Heredi-
tary idiocy is characterised by excessive weakness of memory,
" idiots generally recollecting only what concerns their tastes,
their propensities, their passions. But as this is doubtless the
result of the feebleness of their sensorial impressions, this
heredity is the effect of a more general hereditary transmis-
sion." Even history affords but few marked instances, but
there can be no doubt that artists, whether pictorial or
musical, must inherit, respectively, a good memory for forms
and colours, and for sounds ; and as a matter of fact these
have been transmitted through four or five consecutive
generations. " It must be admitted," says Ribot, " that
there are not many facts to show the heredity of memory ;
but the conclusion is not thereby justified that this form of
heredity is rarer than others. The opposite opinion is still
tenable, and the lack of evidences can be explained.
Memory, with all its undoubted usefulness, plays in human
life, and consequently in history, only a secondary and

54

obscure part. It produces no work, like the intellect and
the imagination, nor does it perform any brilliant actions
like the will. It does not give material evidence of itself,
like a defect of the senses. It does not come under the ken
of the law, like the passions ; nor does it enter the domain
of medicine, like mental disease. Since, then, it is so little
tangible, the lack of evidences need not surprise us ; and
there is still reason to hope that, in proportion as the sub-
ject of mental heredity, hitherto much overlooked, is better
studied, attention will be directed to this matter, and will
abundantly show that here, as elsewhere, heredity is the
rule."

Chiefly concerning fictitious instead of real objects, the
Imaginative faculty may be said to differ in its character in
some respects from that of Reason ; yet in both the same
powers are exercised, though in a different manner. The
Imagination, then, depends upon the intellectual powers for
all its higher operations, and is usually recognised to be of
a twofold character — viz., reproductive and creative, both of
which are hereditarily transmissible. Perception and
imagination being correlated so intimately, we can readily
understand the transmissibility of the latter ; and besides
the first and instinct, imagination, as a faculty of the mind,
is more commonly transmitted than any other. We are here
more intimately concerned with the creative or active form
of imagination — " the imagination which creates and
interprets an ideal conception by means of sensible forms "
— in a word, the imagination of poets, painters, musicians,
and scientists. Of the four subjects just mentioned, whilst
the imagination of all is emphatically hereditary, the
families of poets are, perhaps, more comparatively rare, and
this is scarcely to be wondered at when we remember that

55

the physiological conditions necessary for the development
of a painter or musician are not necessary to the same
extent, at least, for the cultivation of the poetic faculty.
Thus the painter must have an innate gift for colour and
form, and the musician an innate gift for the appreciation of
the most exquisite varieties and combinations of sound ;
and thus the talent of the artist or the musician must depend
more on the conformation of the organs than that of the
poet. The history of art, however, shows unmistakably
that this active or creative imagination, whether of poets,
painters, musicians, or scientists, is hereditarily transmissible,
and it would be an easy task to cite very numerous
instances in proof of the assertion. Suffice it to say that as
the result of an examination of the families of fifty-one
distinguished poets, twenty-two of them have had one or
more distinguished relatives. Amongst painters, whilst we
have in England the Landseers, and in France the Bonheurs,
Galton found, in a list of forty-two painters of the highest
rank, Italian, Spanish, and Flemish, that twenty-one had
illustrious relatives. Of musicians, the Bach, family is,
perhaps, the most distinguished instance of mental heredity
on record. In this family alone, of whom Fetis mentions
fifty-seven members, twenty-nine are described as eminent
musicians. The Bendas, Mendelssohns, and Mozarts afford
also numerous instances. These facts put it beyond all
doubt that the imaginative faculty is potentially transmissible
by heredity.

Having thus far considered the heredity of perception,
memory, and imagination, I must now inquire whether the
remaining faculties of the mind — which concern themselves
with abstract and general conceptions — are subject to the
same law. "Are the higher," as Ribot asks, "like the

56

lower modes of intellect transmissible ? Are our faculties
of abstraction, judgment, ratiocination, invention, governed
by heredity, as are our perceptive faculties ? Are common
sense, insanity, genius, talent, subtlety, aptitude for abstract
studies, hereditary ? " As the unity of the intellect is
recognised and admitted by all schools of thought, and as
facts undoubtedly prove the heredity of the lower intellectual
modes, it must follow as a natural sequence that all the
higher forms of the human intellect are also subject to this
law. However deeply we inquire into the ultimate nature of
intellect, we must accept either one or the other of the two
following conclusions : We must either hold, with the
materialists, that it is phenomenal, the cause being the
organism ; or with the idealists, that it is noumenal, the
effect being all that exists or can be known. The materialistic
argument is as follows : — " If thought is only a property of
living matter, then, as heredity is one of the laws of life, it
must therefore be also one of the laws of thought ; or, in
more precise terms, intellect is a function whose organ is the
brain ; the brain is transmissible, as is every other organ,
the stomach, the lungs, and the heart ; the function is
transmissible with the organ ; therefore intellect is trans-
missible with the brain. Physiological heredity involves, as
a necessary consequence, psychological heredity in all its
forms."

In contradistinction to this theory is that of the idealists,
who hold thought to be the only reality, and who, with
Schopenhauer and his school, discover in will the first cause
of all things, the supreme reality. Like all other systems,
this " must account for the world of sense, for nature, and
her phenomena and laws. There being no other absolute
existence, save thought, matter must be referred to thought."

57

It must admit the material world, with its laws, as a purely
phenomenal existence, and this admission enables us to see
that the opposition between the materialistic and idealistic
theories is by no means so radical as it would at first appear,
and that there is a possible reconciliation between the two.
Schopenhauer and his following believe that " there are two
di- tinct modes of existence ; the noumenon in the will, and
the phenomenon in the intellect and in nature. To the
mind, regarded as noumenon, none of our conceptions of
laws, logical necessity, or categories, are applicable, for all
this only pertains to the mind considered as phenomenon.
Consequently, since we restrict ourselves to the study of
experience — that is to say, of facts and their laws — there can
be no disagreement between us and the idealists. The differ-
ence between us springs, not from any diametrical opposition
of doctrine, but from the fact that to the study of pheno-
mena, which both sides pursue, and to which we strictly
confine ourselves, the idealist joins a metaphysical theory,
which, in our eyes, has no scientific value, since it tran-
scends science. ... If the idealist admits, as he does,
that in the order of physical, chemical, physiological, and
psychological facts there are co-existences and sequences
that can be reduced to fixed formulas, he has no fair
ground for refusing to concede to heredity a place among
these empiric laws, though he may deny that it applies
to the intellect considered as noumenon." The real nature
of thought itself baffles all scientific definition ; for
"although it explains all things, it does not explain itself;"
although, by its means, we may be enabled to solve the
mystery of the universe, it remains in itself a mystery and
insoluble. The unity of the intellect being, however,
beyond doubt, nothing could be less rational than to imagine

58

that any intellectual modes of activity are specifically beyond
the laws of heredity. As scientists, we are only concerned
with the interpretation and recognition of facts, and with
experience, so that with regard to reason — as to the nature
of which even metaphysicians are themselves by no means
agreed — no possible theory can invalidate, or even oppose
our premises, for " the world of pure reason begins only
where the world of phenomena ends " — and thus the scien-
tists and metaphysicians have each separate provinces.
Cousin and Reid define reason as "an impersonal, universal,
and necessary " faculty ; but can we not say as much of
heredity ? These characters being the same " everywhere,
always, and in all men," they are, therefore, specifically
characteristic, and such specific characteristics without
exception, it is the province of heredity to transmit; thus,
according to this definition of reason, " no faculty of man
is more certainly transmissible than the highest form of
intellect — reason. For heredity, too, is impersonal, since
it preserves the species; and universal, since it governs
the whole domain of life ; and it is one of the forms of
inflexible necessity." If we, therefore, regard intellect and
reason from a transcendental point of view, they transcend
experience ; but if we consider them phenomenally, there
is no reason why they should be exempted from the law of
heredity. Our contention that the human intellect, even in
its highest forms, is hereditarily transmissible, in order to be
justified should be supported by numerous facts ; these
indeed are forthcoming in abundance, but for a detailed
list of instances of intellectual heredity among men of
science, philosophers, political economists, historians, critics,
novelists, etc., I can only refer the reader to the evidences
given in Ribot's splendid work.

59

With regard to the heredity of the sentiments and passions,
Ribot says : " Man is situated in the midst of the universe,
which acts upon him only by its properties. Colours, odours,
savours, forms, resistances, movements, become modes of
our organism, producing therein a shock to the nerves.
Then all these peripheric impressions pass to the brain, pro-
bably into the optic thalami, and being thence transmitted
to the cortical substance of the brain, they are transformed,
we know not how, into facts of consciousness ; the physio-
logical phenomenon becomes psychological, constituting
that state of the mind which we denominate cognition.
But this is not all. The nerve-vibrations produced by
material objects, not only make us acquainted with some-
thing outside of us, but they also produce within us a
certain agreeable or disagreeable state, which we call feeling."
If there were no such reverberation of pleasure or pain
within us, then our experiences of the external world would
be, as Bichat says, " only a frigid series of intellectual
phenomena. . . ." If we add that pleasure and pain may be
excited in us either by some state of our organs dependent
on the vital processes, or by recollections suggested by
memory, we have enumerated every mode of cognition
which can produce phenomena of sensation.

Philosophical physiologists, such as Bain, Miiller, and
Maudsley, agree in regarding Spinoza as the author of the
grandest contribution to the philosophical study of the
ultimate reason of sensible phenomena ; and, in his admir-
able Ethics^ the latter author contends that the ultimate
explanation of all sensible phenomena is found in the fact
of desire — "desire meaning appetite with self-consciousness,"
and appetite being " the very essence of man, in so far as
it is directed to acts which tend towards his conservation."

6o

The law of self-conservation has been thus formulated by
Bain : "States of pleasure are connected with an increase,
states of pain with an abatement, of some or all of the vital
functions ;" but the cause of the two states is desire, as it is
just because there are in us tendencies that may be satisfied
or appeased — that we feel pleasure or pain. In fact, when
we experience pleasure or pain, we wish to preserve the one
and destroy the other. In this law of pleasure and pain,
we have the key to the leading varieties and expressions of
the feelings, and it is named the law of self-conservation,
because without it the system could not be maintained,
for, as Bain says : " Inasmuch as we follow pleasure and
avoid pain, if pleasure were injurious and pain wholesome,
we should incur entire shipwreck of our vitality, as we often
partially do, through certain tendencies that are exceptional
to the general law." The law of pleasure and pain we regard
therefore as fundamental : the law that connects pleasure
with increase of vital power ; pain with the diminution of
vital power. In fact we may look upon this law as, in many
respects, the foundation, the main-stay of our being ; it is
the principle of self-conservation — the self-regulating, self-
acting impulse of the animal system.

" The phenomena of the affections," says Ribot, pertain
to our inmost being. By this fact of cognition the outer
world is let in upon us, and is reproduced in miniature,
for thought is nothing but existence arriving at self-con-
sciousness ; but our feeble personality is associated with
this impersonal state by the pleasures and pains it produces
in us, for sensation and volition make us what we are. The
modes of sensibility are so intimately connected with the
organs, and with the whole constitution that, a priori, we
might conclude that they are transmitted by heredity." The

6i

following facts will tend to show whether they are, or are
not hereditarily transmissible.

Buffon says : " A horse that is naturally vicious, sulky,
and restive, will beget foals with the same character ; " a fact
of which every horse-breeder is well aware.

Girou de Burzareingues says : " Heredity may, even in
animals, extend to their most whimsical peculiarities. A
hound taken from the teat, and bred far away from either
parent, was incorrigibly obstinate and gun-shy in circum-
stances where other dogs were easily excited. When a
bystander expressed his surprise, he was told that there was
nothing remarkable, 'his father was the same.'" I might
readily quote other and numerous instances bearing upon
the no less striking transmission of characters when races
and species are crossed, but I shall content myself by
observing that all such evidence of the heredity of pro-
pensities, instincts, and passions in animals, tends to show
that the same qualities are hereditarily transmissible in man,
as it does not necessitate the superficial explanations drawn
from education, example, habit, and all the external causes
which have been supposed to do duty for heredity. In
man, the universal consciousness of existence — that inner
sense of touch whereby we are cognisant of the state of
our organs, of the tension or relaxation of our muscles, of
the state of weariness, pleasure, etc., — is undoubtedly trans-
missible, and the heredity of certain strange propensities,
instincts, and dislikes, may be referred to such an uncon-
scious mode, underlying all consciousness and all thought.
Thus also may be explained the idiosyncrasies of families
and individuals as to the untoward effects of certain drugs,
etc. Montaigne, as is well-known, had an invincible repug-
nance for medicine of every kind, and this he asserts was

62

inherited, in both direct and indirect lines, through many
generations of his family. In connection with thirst, hunger,
and sexual appetite, innumerable instances might be given
as to the heredity of dipsomania, gluttony and erotism, so
also with the more complex passions as gambling, avarice,
theft, and murder, all of which are unquestionably subject
to the law of heredity.

In proceeding to briefly consider the heredity of the Will,
I must be careful in the outset to define what I mean by the
term, and to guard myself from all metaphysical discussions
about free-will and heredity, which have caused so much
wrangling amongst philosophers and theologians. Still,
concerning myself with phenomena and experience — the
true domain of science, — and having already considered the
contemplative faculties of the mind, as to their heredity, I
am now anxious to show that the active faculties of mind,
as represented by the term Will (and all that it implies), are
alike subject to the law of heredity.

"The will, volition, or voluntary action is," says Bain, "on
the outside, a physical fact. Animal muscle under nervous
stimulation is one of the mechanical prime movers ; the
motive power of muscle is as purely physical as the motive
power of steam ; food is to the one what fuel is to the other.
The distinguishing peculiarity of our voluntary movements
is that they take their rise in feeling, and are guided by
intellect ; hence, so far as will is concerned, the problem of
physical and mental concomitance is still a problem, either
of feeling or of intellect. There are three elements in the
will: (i) the spontaneous energy or surplus activity of the
system ; (2) the fundamental law of pleasure and pain, and
(3) a large superstructure of acquired connexions between
feelings and specific movements. With regard to the first,,

63

involving the disposition of the moving organs to come into
operation of themselves previous to and apart from the
stimulation of the senses or the feelings — the activity being
increased when such stimulation concurs with the primitive
spontaneity — I think there is evidence so show that the pro-
fuse activity attendant on health, nourishment, youth, and a
peculiar temperament called the active temperament, springs
in a very great degree from inherent active power, with no
purpose at first, but merely to expend itself, and that such
activity gradually comes under the guidance of the feelings
and purposes of the animal. It is the surplus nervous power
of the system discharging itself without waiting for the
promptings of sensation. In the course of education the
spontaneity is so linked with our feelings as to be an instru-
ment of our well-being, in promoting pleasures and removing
pains. The voice, by mere spontaneity, sends forth sounds;
the ear controls and directs them into melody, and the wants
of the system generally make them useful in other ways.
Mere spontaneity, however, would not give us all that we
find in the impulses of the will. Being the overflow of vital
power, it would show itself only whenever and wherever
there is such an overflow. We want a kind of activity that
shall start forth at any time when pleasure is to be secured,
or pain to be banished, and that shall be directed to the very
points where these effects can be commanded. This power
is exemplified in the fundamental law of pleasure and pain
to which I have already referred. Such I conceive to be the
groundwork of volition, greatly, but never entirely, overlaid
in mature life by a process of education or acquirement."1

In dealing with the heredity of the will the analytical
method hitherto pursued, concerning the heredity of instinct,
i Professor Bain's " Mind and Body."

64

perception, imagination, memory, intellect, sentiments and
passions, will no longer suffice, for with men of action and
resolute will-power the play of the various faculties must be
simultaneous — their processes essentially synthetic, action
alone is their end, theory but a means. Thus they are
characterised by immense resolution and great strength of
will, always exercised, and by the qualities which this implies
— viz., boldness, courage, self-confidence, and mastery over
the timid and irresolute. "Like every other faculty, strength
of will may be hereditary." Voltaire thus writes of the
Guises : "The physical, which is 'father of the moral,' trans-
mits the same character from father to son for ages. The
Appii were ever proud and inflexible ; the Catos always
austere. The whole line of the Guises was bold, rash,
factious, full of the most insolent pride, and of the most
winning politeness. From Frangois de Guise down to that
one who, all alone, and unexpectedly, put himself at the
head of the people of Naples, they were all — in look, cour-
age, and character — above ordinary men. I have seen full-
length portraits of Frangois de Guise, of Balafre, and his
son : they are all six feet high, and they all possess the same
features ; there is the same courage, the same audacity on
the brow, in the eyes, and in the attitude." " We know not,"
says Ribot, "how the will is thus transmitted ; but when we
see that its energy and its weakness are connected with
certain states of the organism, and that physical strength
commonly renders men bold and courageous, while physical
weakness makes them timid, we can scarcely doubt that this
transmission takes place by means of the organs, and that it
is in fact physiological."

Statesmen and soldiers afford the best examples of those
in whom the active faculties of the mind, represented by a

65

vigorous will, are generally found in their highest develop-
ment, and of those who, cceteris paribus, would be likely to
transmit their extraordinary will-power to their descendants.
History affords many illustrious examples : for instance,
amongst* statesmen the Guises, the Medicis, the Foxes, the
Peels, the Pitts, the Sheridans, and the Walpoles ; amongst
distinguished soldiers Alexander the Great, Bonaparte,
Charlemagne, Coligny, Gustavus Adolphus, Hannibal,
Maurice of Nassau, the Napiers, etc., etc., enough at any
rate to disprove all idea of accidental coincidence.

I may here allude briefly to the influence of heredity in
the formation of national character, in contradistinction to
that of individuals; and it is indisputable that, as in a
family, heredity transmits and perpetuates certain physio-
logical and psychological characters, so it transmits and
fixes the physiological and psychological characteristics of
peoples and nations. The character of a nation is but the
aggregate of the characters of the individuals composing it,
and it consequently follows as a logical sequence that what
is thus true of individuals, must also apply to the nations
which they compose. The virtues and vices, the strength
and the weakness, the success or non-success of a nation is
after all but the reflex of the national character ; and we
must regard physiological and psychological laws as the
^reat factors in the building up of every character, whether
individual or national. The institutions of a nation are the
outcome of the people's conduct and religious beliefs : "their
manners and creeds are the effect of their character. The
character produces the institution, and they in turn form the
character ; thus, after several generations, the two are but
one, the institutions are but the character rendered visible
and permanent." "Still," as Ribot continues, "we must

66

not forget that the institutions are only an external cause,
which is sustained by an internal cause — character — and
this is transmitted hereditarily. And as a people is per-
petuated by generation ; as it is a law of nature that like
shall produce like ; as the exceptions to this law tend to
disappear when large masses, instead of particular cases, are
examined, obvious facts point out how national character is
preserved by heredity."

If we examine carefully the history of any nation, we
cannot but become impressed by the light it throws upon the
causes which have led to the people's progress or decline ;
and these causes undoubtedly have their origin and develop-
ment in the national character. How tenacious national
characters are may be seen from the history of the ancient
Greeks, Byzantines, and modern Greeks. " Thus," says
Ampere, " amid all these vicissitudes, the fundamental
character of the Greek has not changed ; he has now the
same qualities, the same defects, as of old." And as
showing how native characters and habits have been trans-
mitted, I need only point out that the Arcadians " still lead
a pastoral life;" whilst their neighbours, the Spartans, "have
a love for fighting, and an excitable, quarrelsome temper."
Surely the following description of our French neighbours,
from the pen of Julius Caesar, is as characteristic as if
written in the nineteenth century. " The Gauls," he says,
have a love of revolution ; they allow themselves to be led
by false reports into acts they afterwards regret, and into
decisions on the most important events ; they are depressed
by reverses ; they are as ready to go to war without cause,
as they are weak and powerless in the hour of defeat." The
history of every nation affords much information as to the
part played by heredity in the formation and perpetuation of

67

its national character, and even when different nations are
crossed by inter-alliances — as sometimes happens for their
weal, and ofttimes for their woe — however the national
character may be thus modified, heredity is the power which
either conserves their greatness, or ministers to their decline;
for it is inexorable in its results. The development of the
highest civilisation is, perhaps, unattainable without that
complexity and variability of elements which are only to be
found as the results of appropriate international fusion ; and
thus development and progress become possible ; but in the
case of even the most exclusive nations, such as the Jews,
the Gypsies, and the Cagots — however their development is
retarded by their exclusiveness — the evolution and fixation
of their national characteriscics is primarily the result of
heredity.

The individuality of man consists in his differentiation
from every other individual — has its source and origin in
heredity, and the modifying principle of variability to
which every individual is subject, and is furthermore
developed and intensified by the results of his environment
in the struggle of life. As no two leaves in a forest are
precisely alike — as no two human faces, however similar,
are the exact likeness of each other ; so no two individuals
who have ever existed have been identically the same,
either in physical conformation, or in mental qualities, or
moral character. Physiologically, we have seen that whilst
the external and internal anatomical conformation and
organic peculiarities are marvellously transmitted from one
generation to another in their minutest details, also the
peculiarities of expression, gait, voice, size, skin, hair,
nails, and everything pertaining to the functions which
constitute the physical life of man ; and whilst also, pyscho-

68

logically, we have seen that instincts, sensorial qualities,
memory, imagination, intellect, sentiments and passions, and
even the human will — everything, in fact, relating to man in
his dynamism — are alike subject to heredity, yet the tendency
to variation, co-existing with heredity in every organic being,
necessitates the differentiation of individuals, and renders
the ideal law of heredity unattainable and impossible.

Regarding a man microcosmically, i.e., trying to analyse
his individuality as to what he is and has organically and
dynamically, we find him evolved from an embryonic vesicle,
the joint production of his parents. Here his individuality
commences. But this same embryonic vesicle has the for-
mative capacity of transmitting with him, not only the physi-
cal, mental, and moral nature of his immediate progenitors,
but also some peculiarities of their ancestors for probably
many generations, so that the source of some of his physical,
mental, or moral peculiarities may have been transmitted
from a remote past. This is indeed a mystery, before which
Science stands baffled and appalled ! The fact, however, is
indisputable. In the brief first stage of life of the unborn
— in addition to the diseases developed in the body while it
is still in the womb of the mother (to which I shall refer
anon) — there occur to the body affections which exercise an
influence over its individuality, and which leave impressions
that last throughout the after-life. Bearing with him, then,
a physical, mental, and moral nature, consisting of qualities,
ancestral, paternal, and maternal, he is at length ushered into
the world, and from the moment of his birth is subjected to
the circumstances constituting his environment, amid which
his struggle for existence must be fought, and amid which
he must be to some extent victorious if he survives. But,
analysing his individuality still further, we find that what

69

we have hitherto defined as physiological and psychologi-
cal may be further subdivided into temperament, idiosyn-
crasy, diathesis, and hereditary predisposition : the first
" applicable to the sum of the physical peculiarities of an
individual, exclusive of all definite tendencies to disease ; "
the second, "a peculiarity of an individual, usually rare,
which does not necessarily entail any degree of proclivity
to disease, but which may become obvious under a variety
of exciting causes ; " the third, *' a bodily condition, how-
ever induced, in virtue of which the individual is, through
a long period, or usually through the whole life, prone to
suffer from some peculiar type of disease ; " x and the last,
any varieties of the three former when transmitted from
parents to children.

The following table will show at a glance the various
factors of individuality, which characterise every individual
in different degrees : —

Ancestral .. Qualities — physical, mental, or moral ^

Parental ... Qualities — physical, mental, and moral V Inherited.

Maternal ... Qualities — generated during uterine life J

Modifications effected by natural variability... Inherited,
/Temperament ... ... \

Ancestral and ' Idiosyncrasy ... ... > Inherited.

Parental. "j Hereditary predisposition... /

N Diathesis ... Inherited or acquired.

Modifications effected by his environment \ . ,
during the life-long struggle for existence /

When it is remembered that every individual is subjected
to each and all of the foregoing influences, and that each,
one of us has inherited certain peculiarities — physiological,
psychological, and pathological — which we, in turn, shall
pass on to our descendants, the reason is not far to seek as
to why every individual differs from every other, or why those

1 Mr. Jonathan Hutchinson.

70

peculiarities which distinguish us from one another in health
should also tend to modify or intensify our relative proneness
to certain morbid affections, by the neutralisation or develop-
ment of the morbid susceptibilities or predispositions which
have been transmitted to us. The physical likeness trans-
mitted by parents to their children is never exact. This is
sufficiently evident in features, size, weight, and all that con-
cerns external conformation. But, as Sir James Paget says :
" If we could be exactly endoscopic, we should observe
equal variation within ; the same want of exact likeness in
liver and lung, and, I venture to say, in blood, and lymph,
and plasma, and whatever goes to make up the whole person,
healthy or diseased. The inheritance of likeness in disease,
or liabilities to disease, is indeed clear evidence of the trans-
mission of likeness in the very minutest part of structure and
composition. But the likeness is never perfect ; it may in
different persons deviate this way or that ; it may vary
towards disease, or back again towards the healthy type ;
but it is never perfect, and, in successive generations, its
degree of unlikeness may in some persons increase to a
great width of difference." We thus see that however perfect
the likeness transmitted from parents to their offspring, it is
never either organically or dynamically exact, and however
closely the partus may resemble the parens physically, men-
tally, or morally ; however closely the former may resemble
the latter with regard to temperament, idiosyncrasy, diathesis,
and hereditary predisposition, yet each child preserves its
own individuality, by reason of the differentiation produced
by natural variability, to which every organic being is sub-
jected, in addition to heredity.

I have now to consider the pathological aspect of heredity
or the influence of the hereditary element in disease. Let

me "begin by defining our terms. Pathology (literally, a
discourse on pain) may be defined as the. science which treats
of the origin, nature, course, and causes of those changes in
the body which constitute disease, or as the physiology of
disease. What, then, is meant by the term disease ? " By
disease is understood some deviation from the state of health ;
a deviation consisting for the most part in an alteration in
the functions, properties, or structure of some tissue or organ,
owing to which its office in the economy is no longer per-
formed in accordance with the normal standard."1 Diseases
.are generally regarded as consisting of two classes — viz.,
organic and functional The terms health and disease are
.alike relative and indefinite ; neither health nor disease being
separable from each other by any hard and fast line, and the
one passing into the other by insensible degrees, just as
physiology passes insensibly into psychology. Disease is
then, generally, an abnormal performance of the vital pro-
cesses nutrition and function^ the latter being especially
dependent upon the state of the former. When, therefore,
both of these processes are normal, the condition is one of
health ; when abnormal, one of disease. Diseases are, there-
fore, not entities, but mere groups of modifications of
structures already in existence, and of actions always pro-
gressing in a vital system. They are, in fact, particular
conditions of the living body — new phases of its vital mani-
festations —whether of the nature of functional derangements,
or of organic or textural degeneracy. Sir John Forbes says : —
" All morbid action is but a modification or perversion of
.some natural or normal action or function; and all the
physical results constituting morbid structural alterations are
mere perversions or modifications of natural or normal
Green's "Pathology."

72

textures, or, at most, analogous textures fabricated from the
same materials by tike processes." Not only in epidemic
diseases, but in all diseases, whether acute or chronic, it is a
matter of universal and daily observation that the pheno-
mena and results of disease are very much modified by the
difference of individual constitutions : and to this difference
must be attributed the special character given to the same
malady in different individuals, as, owing to this cause, we
find the same diseases, under precisely similar treatment, at
the same time exhibit phenomena, progress, and events
entirely different.

We have already seen that the differentiation of indi-
viduals intimately concerns not only their physical nature
and functions, but also their mental qualities and moral
character. Let me briefly inquire how this individuality
affects the morbid processes, whether functional or organic^
to which we are all more or less liable, and to some of
which, in the natural course of events, we must all succumb.
As, in general terms, all that we have and are we owe to
heredity, with the exception of the modifying influences to-
which we are subjected in "the struggle for existence," so,,
as each of us has inherited a certain physical, mental,
and moral constitution, whether healthy or otherwise, and'
differing from that of every other individual, it follows that
this individual differentiation, physical, mental, and moral,
predisposes us, each one more or less, to certain morbid
processes and influences, differing in each as to symptoms,
intensity, course, and mode of termination. As, in fact, the
physiological and psychological nature of every individual
— inherited and acquired — differs from that of every
other, so, too, must every individual differ from every other
as to his pathological predisposition. For example : —

73

Disease germs pass into each of us every day ; but the soil
must be suitable for them to germinate or they produce no
effect ; even when they do germinate the product varies
according to the soil, and, as Sir James Paget says : " The
study of this soil — this living soil — is yet more necessary
in respect of diseases which come in part, or wholly, by
inheritance : for it is in each as personal and distinct as any
other constituent of personal character, and the study of it
must be intimately personal, with an exact analysis of every
disposition to disease" This brief quotation expresses my
argument most pithily, for if it means anything it surely
means that the individuality of each human unit differs
from that of every other, and that by reason of this
individual differentiation — inherited and acquired — every
individual is variously affected by morbid processes and
influences. Would that this great fundamental truth were
more frequently recognised and more highly appreciated by
the members of our profession, for in no other way can we
get rid of that bane of modern practice — routine treatment
— which is neither more nor less than unworthy empiricism !
What is meant by predisposition ? It may be defined as
a sort of neutral state, between health and a state of func-
tional derangement and disease, consisting in a tendency
or liability to, without the actual existence of, derangement
or disease. It might be subdivided under four heads — viz. :
I. Hereditary ; II. ^tal ; III. Sexual ; and IV. Acquired.
With regard to the first, as children resemble their parents,
physically, mentally, and morally, so their constitutional
peculiarities, and the morbid tendencies growing out of
them are also unquestionably inherited. As a general rule,
diseases themselves are not inherited (as we shall see
presently), but only those structural or constitutional peculi-

74

arities which predispose to them. Sometimes, indeed, the
hereditary predisposition is so patent (as frequently seen in
pulmonary and brain affections) that, notwithstanding the
fact of every effort being made to prevent it, the disease
becomes fully developed ; and, just as in physiological
heredity, certain characters or peculiarities remain latent
during an intermediate generation, so also the potency of
atavism or reversional heredity is frequently seen to influence
similarly the phenomena of disease. I shall, however, refer
to this question more in detail in the course of these papers.
Predisposition is also setal, or connected with the age of
individuals, and is most remarkably displayed in infancy for
the following reasons : The skin and mucous membranes of
infants are remarkably delicate ; they are characterised by a
high degree of sensibility or capacity of sensation, also of
contractility or capacity of contraction : the size of the
head is large in proportion to that of the body : they are
exposed to the irritation of dentition ; and they have little
power in maintaining the external heat. After the first
dentition to the sixth or seventh year is a period of great
excitement of the nervous and vascular systems, and
characterised by a predisposition to febrile and inflammatory
affections, also to those of an exanthematous character.
From this up to the age of puberty — a period of comparative
health — the eruptive or exanthematous predisposition con-
tinues, to which may be added a liability to epistaxis, andr
at puberty, those constitutional derangements especially
affecting females, in connection with their uterine functions
and allied conditions. From puberty to manhood — twenty-
four or twenty- five years of age — is a dangerous period,
usually characterised by a strong predisposition to tubercular
and scrofulous diseases, haemorrhages, and digestive dis-

75

orders. The physical and mental health being once confirmed,
remains most vigorous from the twenty-first to the fortieth
year, and the body has then a greater power of adapting
itself to surrounding circumstances. From the forty-fifth
to the fiftieth year, in females, there is a tendency to disease
or derangement of the reproductive system during the
menopause, and, in both sexes after the fiftieth year there
is a loss of strength, certain functional disturbances, a
liability to tissue-degeneracy, and decrease of organic
power. There is, then, as Tanner says, "A predisposition to-
various organic diseases ; the brain, heart, and the genital
and urinary organs being especially prone to suffer. As
senility advances sensibility decreases, the memory fails, the
muscular strength becomes diminished, and gout, calculous
affections, apoplexy, paralysis, softening of the brain, etc.,,
often supervene to hasten on the period of second childhood
to its close. Age has a very important influence on the
same disease occurring in persons of different ages, especially
beyond the middle period of life, for whenever the vitality
of the body, or its different parts, is lessened, then nature is
of course less able to cope with the disease than in young
and vigorous subjects. This is well seen in fevers."

Predisposition is also sexual. There are affections which
appertain peculiarly to males, and others to females, from
the difference of organisation of the sexes. Burns, speaking
of Nature, says : —

" Her 'prentice hand she tried on man,
And then she made the lasses."

and when contrasted with man, there can be no doubt
that she has made use of finer materials in their manufacture ;
for females have, as a rule, a much greater delicacy of the
skin and mucous membrane, and a higher degree of sensi-

76

bility and contractility. So, if we contrast the diseases to
which females are specially liable with those occurring more
characteristically in males, we shall find the former far more
liable to those of an asthenic type than are the latter. Men
are more subject to fatal inflammatory attacks than women ;
they are also more intemperate, and more exposed to violence
and accident. Women, owing especially to the fact of their
having a uterus, are far more predisposed to nervous
affections than men are, and the causes which usually
produce inflammation in men, will frequently, in the case of
women, merely give rise to functional disturbance. The
uterus and its functions, however, give rise to diseases and
disorders in women, from which men are happily free ; for,
during maidenhood there are either excesses, deficiencies,
or other irregularities or complications associated with
menstruation, and during matronhood, pregnancy, delivery,
lactation, and menopause give origin to a " sea of troubles."
Practically, however, the great point to be remembered is
that whilst in man diseases and derangements of a sthenic
character are more frequently observed, in women they are
usually characterised by asthenia and want of tone and
vigour in the nervous system.

Predisposition may be , acquired by a number of agents,
which operate either externally or internally upon the body.
A disorder or disease once affects the body, and having been
removed, leaves behind some weakened part, some latent
fault, which, though not seen under the tranquil state of the
body, becomes disorder or disease when the body receives
a shock. The weak part sustains all the injury when any
exciting cause operates on the body. Thus, again, the
habits of life, mode of living, and nature of occupation, are
amongst the most powerful predisposing causes of — or safe-

77

guards against — disease. So also are climate, temperature,
moisture of atmosphere, and impurity of air. On these,
however, I shall not now dwell, as strictly speaking, in
discussing the hereditary element in disease, I should have
limited my observations to hereditary predisposition alone ;
but as the whole subject is too often lost sight of, I may be
excused for the few remarks I have made on the aetal,
sexual, and acquired sub-divisions. Speaking of predis-
position, Dr. Armstrong says : — " This tendency seems to
have performed a very conspicuous part of ancient pathology,
and is, in my opinion, by far too much neglected by
practitioners in the present day. . . . The doctrine of
predisposition is of the greatest importance in a preventive
point of view ; and if we take the whole of its sources and
trace them through society, we shall find, that in the
civilised world at least, scarcely an individual can be said to
be physically sound. We shall find in almost every person
that there is some latent fault, which may become disorder
or disease when such an occasional agent or cause is applied
as will disturb the body, either generally or locally."
Predisposition, in fact, consists in a peculiar state of the
physical and mental constitution of every individual, which
renders him specially liable to suffer injuriously from the
effects of certain morbific agents ; and when these latter are
of a " non-specific " type, predisposition will determine the
particular disease which it shall induce in each of several
individuals similarly exposed to it ; whilst, in the case of a
specific " agent or " morbid poison," it determines the
relative liability of several individuals similarly exposed to
it, to become the subjects of the particular diseases it is
capable of originating, and also influences the severity of its
attack.1 Thus, let us suppose several persons equally
1 Dr. W. B. Carpenter.

78

exposed to the effects of a chill : some will be found to
suffer no injurious consequences, but one will develop an
attack of pneumonia, another of bronchitis, another apoplexy,
another nephritis, another jaundice, another gout, another
acute rheumatism, another gastro-intestinal derangement,
and so on according to the individual predisposition of each
person. So also, let us imagine several individuals equally
exposed to the influence of some morbid-poison, as of
cholera ; similarly we shall find that, owing to relative
insusceptibility, some of them will pass unscathed through
the ordeal ; others will develop a severe or fatal attack of
cholera ; others will probably only surfer from diarrhoeaic
symptoms, with gastro-intestinal disturbance ; and, again,
others from vomiting, cramps, and characteristic evacuations.
In analysing a man's inherited individuality we have seen
that it depends upon natural variability, and the transmission
of ancestral, parental, and uterine influences ; also that
these inherited qualities may be subdivided into tempera-
ment, idiosyncrasy, hereditary predisposition, and diathesis.
How do these latter affect the predisposition to disease in
individuals ? Temperament, as I have already stated, has
nothing to do with disease in itself, being a part of the
inherited physical and mental constitution of every individual^
irrespective of any morbid tendencies ; but that it becomes
an important factor in predisposing to disease will be seen
from the following facts. It should be here remembered that
the temperaments, sanguine, nervous, lymphatic, bilious,
however well-defined, are seldom or never seen in their
ideally perfect state, for as individuals differ from each other
in every respect, what is true of the whole must also be true
of its parts ; therefore, as a matter of fact, every individual
presents an intermingling of temperaments in different

79

degrees, and thus we see that however potentially tempera-
ment predisposes to diseases, its potentiality will vary with
the individual. Whilst the temperaments are thus generally
"mixed," it will usually be found that one especially prevails,
and may be thus said to characterise the individual. The
modifying influences of the temperaments in disease may
be thus briefly stated. The sanguine temperament predis-
poses to disease characterised by the rapidity of the
inflammatory process, and predisposes its possessors to acute
affections which develop themselves regularly and completely,,
defervesce rapidly, and generally with well-marked symptoms
of crisis. Such persons are especially liable to plethora,
congestions, inflammations, haemorrhages of an active charac-
ter, gout, and inflammatory fever. The nervous temperament
predisposes to disorders of the nervous system, convulsive
diseases, various congestions and haemorrhages, hepatic and
internal obstructions, neuralgia, insanity, and melancholia.
The diseases to which the lymphatic temperament predis-
poses are generally of a chronic character, and of an
asthenic type, as debility, tuberculosis, scrofula, and dropsy;,
and the temperament itself is usually associated with an
inferior power of resistance to attacks of acute disease, and
is characterised by adynamia or slowness of the nervous
and circulatory systems, and by retardation or deficiency of
the general assimilative functions. The bilious temperament
tends to dyspeptic affections, hypochondriasis, and hepatic
derangements generally. It should, however, be remembered
that however highly we may estimate the influence of tem-
peraments in predisposing to disease, they themselves are
capable of being altered in character by age, habit, and
external circumstances, and by the physical and mental
changes originating in disease or accident. The tempera-

8o

ment of any individual may be modified also by suffering,
indulgence, moral control, or religious enthusiasm, and thus
the more we analyse the microcosm of man, the more we
-are astonished by the infinite and ever-increasing differen-
tiation of individuals.

Idiosyncrasy is also a factor in predisposing to disease,
but may likewise become an agent in producing the very
-opposite condition — viz., insusceptibility. Idiosyncrasies
are invariably congenital, and the term is never applied to
those peculiarities which have been acquired. There can
be no doubt that they depend upon peculiarities of physical
structure, however impotent we may be in seeking to
•demonstrate their physical cause. As to their real nature
I regard them — with Mr. Jonathan Hutchinson — as " dia-
theses, or parts of diatheses, developed, intensified, and
.-specialised by hereditary transmission," as, in fact, "diathesis
brought to a point," and the very acme of individuality, for
how often do we see such constitutional peculiarities, in
certain individuals, so intensely developed as to render their
•eccentricity especially striking, if not manifestly absurd?
The phenomena included under the term I am now discus-
sing are variously developed in different individuals, but
"whilst some of them may be neutralised, or otherwise
modified by age and circumstances, all are inherited —
usually last during the whole period of life, more or less —
and are almost invariably transmitted. Idiosyncrasies, like
the temperaments, do not necessarily entail any proclivity
to disease, but may variously predispose to certain morbid
processes, as, for example, the specific or exanthematous
fevers. In the case of one, such an extraordinary immunity
may be revealed that the specific virus may produce no
apparent effect ; whilst in that of another, such an incredible

8i

degree of susceptibility may be manifested, that the virus;
may run riot in his system, producing symptoms of the
utmost violence and intensity. There is at most very little
proof for the assertion that the specific animal poisons vary
in their intensity to any great degree, but at any rate such
variation counts for very little when compared with that
manifested in different individuals exposed to the influences
of the same epidemic, and under similar circumstances.
Scarlet-fever, small-pox, typhus and typhoid, diphtheria,,
erysipelas, syphilis, carbuncle, tetanus : how variously are
different individuals affected by each of these ? Not one,
but many volumes might be written as to the agency
exercised by idiosyncrasy in predisposing to, and modifying
disease, but I shall conclude my observations on this
interesting subject by quoting from Mr. Jonathan Hutchinsonr,
who has done so much to throw light upon the influence
of heredity in disease, and who says : — " If we fail to
recognise, or if we forget, the influences of idiosyncrasy, we
shall not only waste much time in our processes of clinical?
research, but we shall be in constant danger of coming to
wrong conclusions by declining to accept evidence as to
cause which is really sound, and of adopting false principles
in reference to treatment. In every example of a curious
and unexpected form of disease, our minds should, I think,
first ask the question, * How much of this may possibly be
due to the individual peculiarities of its subject ?' We are
often on a wrong track if we seek to make external influences
explain the whole. It seems to me of great practical moment
that the individual peculiarities of all patients should be
carefully studied and that they should themselves be made
intelligently acquainted with them. There are few of us
without our idiosyncrasies, and their variety is innumerable."'

82

Diathesis may be defined as a term denoting a morbid
proclivity existing in an individual or family in consequence of
his or their heredity and environment; or, still better, as "any
condition of prolonged peculiarity of health giving proclivity
to definite forms of disease." Mr. Hutchinson says : "What
we mean by diathesis is little other than an exceedingly
chronic disease. It is a disease or taint which lasts a life-
time, which may be active at times, and latent at times, and
which may be handed on to another generation." Diathesis
may be either inherited or acquired — may be permanent or
transitory, or intercurrent with healthy intervals. The term,
strictly speaking, should never be associated with any transi-
tory condition of health which may pass away without leaving
any permanent impression upon the system, for persistency
to some extent is invariably implied by it. It is also
necessary to distinguish between the terms dyscrasia and
diathesis, for, whilst the former signifies actual bad health,
the latter simply implies a morbid proclivity which may be
possessed by an individual who is seemingly quite well.

As to the causation of diatheses, it is well to remember
that as the health or unhealth of races, families or individuals,
is dependent upon transmitted tendencies, owing to the
action and interaction of the law of heredity in their pro-
genitors, and also upon the action of circumstances upon
themselves, the morbid peculiarities whose general pheno-
mena are grouped under the term diathesis, must depend
entirely upon the same causes. These exist hereditarily in
the individual, and, in the acquired form, in the circum-
stances of his environment — the latter also accounting for
the development of those which have been inherited. I
shall now very briefly consider the classification of the
•diatheses, or those types of morbid proclivity which dis-

83

tinguish individuals, and the due recognition of which so
intimately concerns the processes of disease and their
treatment.

To supply any adequately satisfactory classification of the
diatheses is simply an impossibility, owing principally to the
facts that our present knowledge of them is far too vague
and imperfect, and that their relative differentiation is very
frequently dissimilar in kind. It would be easy enough to
classify diatheses under such heads as temporary and per-
manent— acquired and inherited, but in such a classification
it would be often necessary to place the same morbid con-
dition under more than one class, which would, therefore,
lead to confusion and complexity. I shall, therefore, whilst
glancing at the classification of the older writers, materially
adopt that of Mr. Jonathan Hutchinson, which is formed on
a more scientific basis, and bears more particularly upon the
life-history of pathological processes. In the text-books of
a few decades ago we find the recognition of the following
diatheses — viz., the gouty, rheumatic, cancerous, tubercular,
and strumous. The two first are still recognised, but the
third is now acknowledged to be a dyscrasia rather than a
diathesis, and the two last are generally associated together,
as consequences of inflammatory action in predisposed
individuals. Curiously enough, Professor Laycock (to whom
we owe so much in everything pertaining to the differences
between man and man), in enumerating his classification of
the diatheses, gives the following — viz., the arthritic, the
strumous, the nervous, the bilious, and the lymphatic. Dr.
Milner Fothergill follows suit. But, to my mind, both of
these authorities are mistaken in mixing up temperaments
with diatheses, and in not estimating the differences between
them. For, as the temperaments are purely physiological,

84

and involve no tendency to disease, the diatheses, on the
other hand, are purely pathological, and consist essentially
of a morbid proclivity. Thus the last three diatheses
mentioned in this classification should be relegated to the
temperaments, as they concern only the physiological differ-
ences between man and man, and do not necessarily imply
any predisposition to disease.

It may be here mentioned that whilst we regard a diathesis
as a constitution of body which, in the course of life, at
various periods, and under varying circumstances, will give
rise to local or general diseases, characterised by a common
resemblance, either as to their etiology, . symptoms, or
pathology, and thus constituting a unity, yet the various
diatheses, owing to the action and interaction of heredity
and environment, combine with each other in various
degrees, and thus result in complex or composite diathetic
varieties. For like heredity, without evolution, if the
diatheses were transmitted without variability, they would be
indefinitely inherited with the same specific characters, which
we know would not be in consonance with natural law.
And thus, in practice, every day of our lives, we meet with
patients who, while they afford us typical examples of this or
that diathesis, yet reveal the elements of others in various
degrees. As the so-called laws of Nature represent merely
the grouping of certain phenomena, so diathesis may be
regarded as the grouping of certain constitutional pecu-
liarities, having certain pathological tendencies, in certain
families or individuals ; and, as every individual differs from
every other, in every respect, we must naturally be prepared
to admit a similar differentiation with regard to his diathetic
peculiarities. Diatheses are, in fact, but rough types of
constitutional peculiarities, showing a predisposition to

85

certain diseases, and which may be variously blended in
different individuals, whilst the original type is more or less
preserved. I now enumerate the classification of diatheses
given by Mr. Jonathan Hutchinson, which is as follows : —

The scrofulous or tubercular ^

The rheumatic ^Universal.

The catarrhal J

The malarial 1 -,..

V Climatic.
The bronchocele J

The gouty and hsemorrhagic A

The leprous [Dietetic.

The scorbutic f

The rachitic /

The diathesis of malignant new growths.

The diathesis of senile degeneration.

The visceral diathesis.

Specialised diathesis (chilblains, feeble vascularity, etc.)

I shall now briefly consider the foregoing diathetic varieties
as exemplifying not only the influence of heredity in pre-
disposing to disease, but its power as a factor in differentiating
man from man in his morbid predispositions.

The Scrofulous and Tubercular Diathesis. — I regard scro-
fula and tuberculosis as modifications of the same inflam-
matory process — the former usually resulting in the develop-
ment of tubercle, although the typical inflammatory process
of scrofula may not attain a distinctly tuberculous condition.
At the same time, the proneness to tuberculosis may be so
potent that it is produced as a lymphatic neoplasm, without
an inflammatory exciting cause, and without the occurrence
of preceding congestion. In the case of both forms of
inflammation a predisposing, as well as an exciting cause, is
generally present — the first being hereditary, and the second
acquired — and the greater the degree of the former, the less
is the need for the latter. Thus we see that as in scrofula so

86

also in tuberculosis, both are the results of inflammatory
action in predisposed individuals.1

Beyond a few differences there is nothing in the physical
conformation of the scrofulous which does not represent that
of the tuberculous. The scrofulous, the rheumatic, and the
catarrhal, Mr. Hutchinson regards as the three great universal
diatheses to which every individual is more or less subject
— the degree of susceptibility varying extremely in different
individuals ; and in many cases so great is the susceptibility
that in itself it constitutes a very grave and critical disease.
The scrofulous diathesis is almost invariably inherited, but
is sometimes developed by all those external circum-
stances which tend to reduce the natural powers of the con-
stitution. This diathesis, whilst it is the parent of many
•evils, is not in itself so well-defined as others, and is
frequently associated with abnormal states of the circulation,
which have probably no connection whatever with tuberculosis
— viz., the liability to chilblains, swollen lips, etc. The ten-
dency of modern thought is, however, to regard both scrofula
and tuberculosis as modifications of the same inflammatory
process, and the two diatheses generally associated with
them are now regarded as modifications of the same diathesis.

The scrofulous diathesis, whilst ill-defined in itself, is very
frequently associated with others, as those of gout, rickets,
and goitrous cretins, and, in fact, with all those diathetic
predispositions which tend to degeneration of nutrition in
general. Although commonly associated with the lymphatic
temperament, the latter does not, therefore, necessarily imply
scrofula : indeed, scrofula may be well marked in those of
the sanguine, or of the melancholic temperament. However
little may be known of the real intimate nature of scrofula,
xMr. Jonathan Hutchinson.

87

we are at least assured that it is associated with defective
vitality ; that it is markedly hereditary, and that its diathesis
involves a special predisposition to the many forms of
scrofulous or tuberculous diseases.

The Rheumatic Diathesis. — Two forms of this diathesis
have been described — viz., the vascular, allied to gout, and
the strumous, with external characteristics of scrofula ; thus
showing that, whilst individuals are very frequently found
who are distinct and typical examples of each form of dia-
thesis, in the case of others there will be one diathesis
forming, as it were, the basis, and another, or others, super-
imposed upon it, as, for instance, the strumous and rachitic
often possess gouty characteristics. Dr. Laycock gives the
following sketch of the physiognomical peculiarities of those
possessing the rheumatic diathesis : " They are usually well-
built and well-nourished, and the complexion healthy and
florid. In those who have the rheumatic cachexia this is
not so, being pallid and dingy, often with patches of pig-
ment deposit. In a certain class with tendency to fibroid
degeneration there is a yellow bronzing of the face; the
teeth are characteristic, being unusually regular, sound, and
firm ; the hair is abundant ; the skin less thin and dry than
in the scrofulous form." This diathesis is distinctly here-
ditary, and tends to run in families. By this is meant not
that the disease itself, but only the family tendency to it, is
transmitted — in a word, a greater or less liability to contract
it. Dr. Maclagan says "The difference between a rheu-
matic and a non-rheumatic subject is, that the motor appa-
! ratus of the former contains that special ingredient which is
\ requisite to the propagation and action of the rheumatic
poison, while that of the other does not. Between the
fibrous tissues of the two men there is no difference that

88

can be detected either by the anatomist or the chemist ;
but in the one these tissues afford a nidus for the propaga-
tion of the rheumatic poison, in the other they do not. In
the one the tissues of the motor apparatus contain some-
thing which is wanting in those of the other. It is the
presence of this something which constitutes the peculiarity
of the rheumatic constitution. It is the tendency to the
development of this peculiarity which is transmitted from
father to son, and makes each generation susceptible to the
rheumatic poison."

Although rheumatism when it occurs in the young is
usually transitory, yet the individual who has once suffered
from an attack will be ever afterwards liable to another, and,
as age creeps on, there is great danger that it may become
chronic, or even permanent. The rheumatic diathesis is
not only found associated with the catarrhal, the scrofulous,
and the gouty, but may be modified by any other condition
or influence which deleteriously affects the general powers
of the system. The rheumatic diathesis becomes so inti-
mately united with the gouty in hereditary transmission that
it is frequently impossible to distinguish between them.
Although no age is exempt from the development of rheu-
matism, attacks are most frequent between the ages of
sixteen and twenty, and the whole cycle of its operation
may be included between the fifteenth and fortieth years.
As already stated, previous attacks decidedly increase the
predisposition to the disease, and although ill-health, how-
ever induced, may predispose to a rheumatic attack, also
mental worry or depression, many individuals are attacked
when in, apparently, robust health.

The Catarrhal Diathesis. — There is an innate proclivity
of tissue, which is hereditary, predisposing to catarrhal

89

affections — in fact, a diathesis, all the individuals who are
subject to which are made more or less liable to the protean
effects of catarrh, and in very varying degrees. As Mr.
Hutchinson, so far as I know, was the first to recognise and
describe this diathesis as such, I shall for the most part use
his own words in referring to it. Catarrh should be held to
imply identity in cause and not similarity in result. By
using the word in this sense — /.*., by not simply regarding
all those forms of inflammation of mucous membranes
attended by free discharge, irrespective of their causes,
which are often very different, as catarrhal, we shall find it
applicable to other forms of inflammation than those merely
of mucous tissues. " In so doing," he says, " we shall
construct a large and perfectly natural group of maladies.
Whatever is the result of catching cold is catarrhal ; con-
ditions which follow from other and dissimilar causes,
however similar their results, ought to be refused that name.
The catarrhal diathesis, using the word in this sense, is one
of the three fundamental ones. It is not due to any specific
or any specialised cause. Every organisation possessing a
nervous system must be supposed to be capable of manifes-
ting it, for its essence consists in proneness to inflammatory
congestions excited, in a reflex manner, through the influence
of cold applied to the surface. The susceptibilities of the
nervous system, however, in this respect differ, as we all
know well, very greatly in different individuals. These
differences are hereditary, and may easily become the
possessions of families or of race. Not only do individuals
differ in the degree of reflex susceptibility, but they also vary
much as to the special tissues or organs which are most
prone to suffer under it. Thus, some catch cold, almost
solely in the mucous membranes of the nasal passages and

90

pharynx ; in others, the tonsils, throat, and larynx are more
prone to suffer ; in others, the bronchial mucous membrane ;
and in others, the stomach and bowels, or even the liver."

I have now briefly sketched the three great universal or
fundamental diatheses, to which probably every human
being is subject in some degree, and which have been
evolved out of the womb of an illimitable past : — which
have been transmitted from age to age, and from generation
to generation, developed and increased, or modified and
repressed, to the present, and which will assuredly, to a
great extent, control the health-destinies of generations yet
unborn, in the future. Each of them involves a specialised
constitution, varying as to specificity in every individual, by
means of which each living person is more or less pre-
disposed to the diseases which these diatheses are, respec-
tively, capable of influencing ; and, in the natural history of
disease itself, there can be no more interesting or important
chapter than that which concerns itself with these diatheses,
— so curious in their origin, so complicated in their action,
and so inevitable in their results.

The Malarial Diathesis. — This diathesis differs from the
preceding ones in being generally acquired instead of
inherited. At the same time, it may be in some degree
hereditary, the transmissible proclivity being in proportion
to the severity and duration of the disease in the parent or
parents. It is, moreover, difficult to discriminate between
what is inherited and what is acquired, as the children of
those who have been subjected to malarial influences are
generally " born under conditions of continued exposure to
its cause." This diathesis may be found associated with any
other ; also with syphilis and alcoholism. Of malaria itself
we know nothing definitely, as its real nature has hitherto

baffled the combined efforts of medical scientists. Its exis-
tence is known to us only by its effect — viz., the production
of the various forms of intermittent and remittent fevers.
With regard to the real nature of the malarial poison, the
most generally believed opinion is that it consists of minute
organisms. Thus Niemeyer says : — " I have no hesitation
in saying decidedly that marsh miasm — malaria — must con-
sist of low vegetable organisms." Certain it is, however,
that the microscope has not yet revealed them ; but as the
powers of this instrument are limited, as is the visual power
of our eyes, it is not, therefore, fair to assume that such
minute organisms do not exist. There is, doubtless, in the
personal constitution of certain individuals a peculiarity,
differing in degree in each, which predisposes them more
or less to the influence of the malarial poison ; and once
the disease has been excited, subsequent attacks may arise
without any exposure to malarial influence, thus proving that
its effect upon the constitutions of affected individuals is
invariably permanent, and that the individual who has once
been subjected to the action of malaria, will not only display
susceptibilities as long as his life lasts, but may pass them on
to his offspring by hereditary transmission. It must, there-
fore, appear that the state of body which we name diathesis
is capable of being produced by an agent so persistent and
permanent in its effects as the malarial poison.

The Bronchocele Diathesis is, like the foregoing, depen-
dent upon certain climatic or telluric influences, and may
be either hereditary or acquired. Bronchocele or goitre
consists in hypertrophy of the thyroid gland ; but in reality
this is merely a prominent symptom of a general morbid
condition, which is endemic, and prevails in magnesian-
limestone districts. Its predisposing causes are hereditary

92

.tendency, the female sex, and the age of puberty. With
regard to its exciting cause, like the poison of malaria, it
has never been satisfactorily determined ; but where the
disease has arisen without being inherited, the cause can
generally be traced to some impurity in the potable water —
probably some form of iron. In this country women are
far more predisposed to bronchocele than men, and although
the disease generally occurs about the age of puberty, it
may occur from any age up to forty years ; and children have
been born with a thyroid enlargement. Just as malaria
belongs to marshy grounds, swamps, and jungles, so the
causes of bronchocele are intimately associated with moun-
tains and valleys, — the most common characteristics of the
spots in which it prevails being want of due movement
in the air, as in deep valleys shut in by mountains.
Frequently associated with bronchocele is " that strange and
melancholy " form of idiocy or imbecility, called Cretinism ;
a condition arising from endemic causes, associated with
imperfect development and deformity of the whole body,
varying, however, in degree. It is developed under the
same conditions as bronchocele ; accordingly it is generally
met with in the same localities. In this country it has
been observed in the dales between Lancashire and
Yorkshire. As in the case of bronchocele, when Cretinism
cannot be traced as the result of hereditary predisposition,
it will be found to depend upon certain atmospheric and
geological conditions, peculiar to special localities. In an
endemic disease like bronchocele, where the general health
is always in a morbid condition, it seems absurd to associate
it only with the enlargement of the thyroid gland, but since
it is hereditary, and reveals itself persistently in those
families which have once been subject to it, it implies an

93

innate morbid proclivity, which can only be represented by
the term diathesis. Contrasted with malaria, the causes of
this diathesis work much more slowly, as a much longer
residence in the locality is essential for the production of
their effects ; and, for their full development, it appears
necessary that hereditary transmission should have existed
through several generations.

Mr. Jonathan Hutchinson insists upon the features of
distinction between diatheses due to food, and those to be
assigned to climate, and says :— " The latter are distinctly
restricted and endemic ; the others not so. The latter,
when severe, affect all immigrants who come within their
range of influence, without regard to health, position, or
habits, and under certain circumstances leave scarcely any
exempt. The diet-diatheses, on the contrary, as illustrated
by leprosy and the like, affect immigrants only very seldom,
-and with great apparent capriciousness, taking one, and
leaving a thousand untouched." I shall now proceed to
briefly discuss these diet-diatheses, which constitute a group
of great importance, and may be regarded as " persistent
constitutional conditions, sometimes hereditary, at others
not so, which have their origin in connection with food."
There can be no doubt that personal habits as to the use
and abuse of certain articles of diet are so capable of
modifying the health of individuals, as to produce in them
such constitutional conditions as will predispose them to
certain diseases, and that this predisposition may become
hereditary. We are therefore justified in including these
morbid proclivities in the category of the diatheses.

The Gouty Diathesis is the first and most important to
be discussed in this class, and it is capable of assuming
widely different forms, and of causing a vast number of

94

symptoms, disturbances, and complications. It is distinctly
hereditary, and may be acquired. The fundamental fact
upon which all theories as to the nature of gout must be
founded is that it must be regarded as a constitutional
disease depending upon the deposition of urate of sodium
in the cartilaginous structures of the joints. The symptoms
of gout are too well known to render their recapitulation
necessary here, nor do I deem it essential to enumerate the
physiognomical peculiarities which may be said to charac-
terise its subjects. The etiological sources of the gouty
diathesis may be traced to hereditary transmission, certain
errors in regard to diet and drink, and the impregnation of
the system with lead. In many cases, however, these
causes may be more or less combined. Try as we may to
eradicate the gouty diathesis, it will be almost inevitably
transmitted for several generations, but as the diathesis is
generally intensified by pernicious habits of eating and
drinking, it will be readily seen why it becomes so frequently
a permanent legacy handed down from one generation to
another. Heredity may be so strong in its production, that
gout may arise without any further cause, and should the
predisposition be very marked, it may even be developed in
children, and the younger the subject the more probable it
is that there is an hereditary taint. The acquired causes of
this diathesis are inordinate or erratic eating and drinking,
and due want of exercise. Even in cases in which there
is hereditary predisposition, these habits will aggravate and
intensify the proclivity. Alcoholic intemperance is also an
important factor in the development of the gouty diathesisr
and is capable of producing the diathesis de novo, in addition
to the influence it exerts on any transmitted proclivity,
In fact, as Mr. Hutchinson says : " Had mankind continued

95

to be vegetable-feeders, and never known the use of wine or
beer, we should have had no experience of gout." It has been
observed that gouty persons are peculiarly susceptible to the
influences of lead in the system, as is proved by the fact
that medicinal doses of this metal have often been known to-
induce an attack. Unless very strongly hereditary, this
diathesis scarcely ever reveals itself before thirty years of
age, and seldom 'after sixty-five : males, probably owing to
the different habits of the two sexes, are, as a rule, much
more predisposed than females. Full-blooded, plethoric
persons are said to be predisposed, but it should be remem-
bered that these conditions are often produced by the habits
which originate acquired gout : formerly this dominus
morborum was also regarded as morbus dominorum, from its
being confined to the aristocracy, and to those in affluent
circumstances, for obvious reasons, but it is now common
enough amongst " people of low degree."

The hamorrhagic diathesis is associated with the gouty
as effect and cause. When once established, this diathesis
is strongly hereditary. It is confined to man, the lower
animals being apparently exempt, and has frequently mani-
fested itself during an attack of gout in certain individuals.
This diathesis, as Mr. Hutchinson has pointed out, " has
its origin in the peculiarities of vascular structure which
are developed by gout, and which have become modified
and specialised by transmission through many generations."
Heredity is,. without doubt, the most striking and important
of all the predisposing causes of this diathesis. Grandidier
speaks of it — Haemophilia — as " the most hereditary of all
hereditary diseases ; " and so potent is heredity in the per-
petuation of this terrible disease, that " it has been possible
to construct an actual family tree of the disease, with roots

96

or main branches running back through several decades,
or even a century and upwards, and ramifying more or less
widely in later times." Whenever this fell disease makes its
appearance in a family, other members are almost certain to
become affected ; and if we compare the total number of
recorded cases with the number of families affected, we shall
find that the number of individuals affected bears a propor-
tion of three to one to the families. Sometimes several
bleeder-children may be born of parents who have never
manifested the disease ; at other times, it becomes developed
gradually through a longer period of time, the anomaly
starting in a single individual, and descending directly
through a series of successive generations. A third, and
very important mode of propagation, is by means of indirect
transmission. " Thus, after one or more cases of haemophilia
have appeared among the children of healthy parents, the
affection is usually handed down, not so much by the
bleeders themselves, as by their non-bleeder brothers and
sisters ; and this singular mode of transmission of the out-
ward manifestations of the disease may be repeated for
several generations." J Thus much for the hereditariness
of this diathesis.

The Leprous Diathesis. — There has been some confusion
generated by the indiscriminate use of the two words
leprosy and lepra to signify the same disease, whereas the
two diseases which they respectively represent are quite
distinct from each other. True leprosy is synonymous with
elephantiasis Groecorum, and lepra Arabum, but the term
lepra as applied by the Greeks represented a disease charac-
terised by scaly white spots on the skin, sometimes
erroneously regarded as psoriasis, but which is unquestion-
1 Imraerman.

97

ably very different and distinct from true leprosy — a terrible
disease — described by Aretaeus as so much greater than the
rest of diseases, as the elephant is bigger than all other
animals — which is generally diffused through the body,
involving more or less its every tissue. Leprosy is endemic
and hereditary, and amongst the other predisposing causes
may be mentioned those which produce scrofula. As to
the exciting causes much difference of opinion still exists,
the late Sir Erasmus Wilson contending that miasma is the
causative agent, while Mr. Jonathan Hutchinson and others
believe that the real cause is a poison taken in connection
with fish. Certainly leprosy has been known to exist and
flourish where malaria is unknown. Mr. Hutchinson thus
summarises the evidence which leads him to place leprosy
amongst the diet-diatheses: — "It is," he says, "the same in
all countries, and probably has been so in all ages. It is the
same in rich and poor, in hot climates, and in cold climates.
It is certainly neither infectious nor contagious ; yet it is
capable of origination in those who go to reside where it is rife.
It slowly gets well in those who leave its haunts and reside
elsewhere. It is not possible to mention any climatic
condition which is common to all the varied localities where
leprosy is found. Whenever it occurs in hot climates it
usually observes the same rule as it does when occurring in
a temperate climate, where it happens to those who are
engaged in the fishing trade, and who live, to a very large
extent, upon the poorer kinds of fish ; yet in hot climates it
now and then happens to those who eat but little fish.
But this is always under circumstances where fish is known
to be bad, and where it rapidly decomposes. Finally, in
all temperate climates leprosy disappears before advancing
civilisation, the introduction of agriculture and the increase

98

of population." After these convincing arguments, I feel
there is no necessity for me to apologise for having included
leprosy amongst the diet-diatheses.

The Rachitic Diathesis. — Rickets may be defined as a
disease of infancy and childhood, producing distortion of
the osseous system owing to a deficiency (or, according to
Sir William Jenner, a malposition,) of calcareous matters,
and of the more essential matters of the bony structure.
The disease is said to be sometimes intra-uterine in origin,
but this seems doubtful ; it usually begins, however, soon
after birth — frequently from the fifth to the sixth month, and
very often makes its appearance first when lactation is
discontinued — reaching its climax and subsiding, when, as
a rule, milk is no longer given as diet, but the child is
allowed to have a variety of mixed food. Although there is
some difference of opinion as to whether it is hereditary or
not, there can be no doubt, at least, that the state of health
and general nutrition of the mother must be ranked as a
predisposing cause of great importance. Those who believe
in its hereditary nature contend that a diathesis allied to, but
not identical with, the scrofulous, is transmitted, but the
tendency of general opinion is, that rickets in the great
majority of cases is not inherited, nor is it a mode of develop-
ment of tuberculosis or of syphilis. I shall, therefore, not
discuss it further here.

The Scorbutic Diathesis is an example of "an acute
diathetic disease produced quickly, and quickly cured,"1
inasmuch as it rapidly subsides and passes away when the
supply of improper food on which it depends is withdrawn,
and when the deficiency of vegetable food, which is its
exciting cause, is supplied. -The principal reason for
1 Mr. Jonathan Hutchinson.

99

regarding it as a diathesis at all is the fact that, as soon as
the acuter symptoms have subsided, it sometimes happens
that it assumes a chronic form, associated with permanent
ill-health ; and not only so, but there is every reason to
believe that the modification of health, so induced, may be
transmitted by heredity.1 Although, therefore, scurvy is a
disease of comparatively short duration, it is capable
occasionally of not only modifying the health, but of
transmitting its influence hereditarily; and as its essential
cause is as stated, a defective diet, there is every reason why
it should be included among the food-diatheses.

The Diathesis of Morbid New Growths, — This term is
employed by Mr. Hutchinson to denote " cancer in its old
and popular sense, as including malignant new growths of
all kinds ;" and as we have the term carcinoma, as opposed
to sarcoma, by which to differentiate certain malignant new
growths from others, he regrets that the word cancer is not
still retained to designate all kinds of malignant new growths,
which, in examining as to diathesis, must all be grouped
into one family, so that the individual tendencies to new
growths in general should be estimated without over-
regarding differences of kind, especially as " some persons
display more than one form, and when hereditary trans-
mission occurs it is very common to see it produce a growth
of a different kind from the original." I must be careful to
distinguish between the terms diathesis and dyscrasia in
relation to cancerous growths, for as the former signifies
merely an inherent proclivity to cancer in the tissues, the
latter concerns the actual development of cancer in .the
body, with its associated ill-health. Is there any condition
of tissue-health, pre-existing before the actual development

1 Ibid.

100*

of cancer, which may be said to give proclivity to it ? If so,,
the term cancerous diathesis may be justly applied to such
a condition. As Mr. Hutchinson points out, " Cancer in
the main is obviously dependent upon age ; it is in nine
cases out of ten part of senility — a sort of second childhood
of the tissues. . . . We shall probably be not far from
the truth if we admit senility of tissues, local or general, to
be the one predisposing cause of cancer with which we are
acquainted : whilst injuries and all forms of local irritation
are its exciting causes. A little step further may next be
taken in the belief that everything which tends to hasten
senility, either local or general, will increase the .predisposing
influence, and in this category may be placed anxiety,
distress, overwork, and excesses of all kinds."

That the development of all malignant tumours or growths
is materially influenced by constitutional conditions admits
of no doubt ; also that neoplastic processes when occurring
locally may be, and are generally, modified by the general
state of the constitution : moreover, in the case of malig-
nant new growths, this constitutional or diathetic condition
is undoubtedly capable of determining the development of
the neoplasm. The influence of hereditary predisposition
as an etiological source of new growths, is, indeed, all-
important : as Dr. Green says : — " The inherited peculiarity
is probably, in most cases, a local rather than a general
one, consisting in some peculiarity of the constitution affec-
ting the tissues from which the new growths originate, some
peculiarity which renders them more prone than other
tissues to undergo abnormal development : .
the tendency would appear to consist in a predisposition of
the tissues themselves to become the seats of new forma-
tions." Whether we may agree with Dr. Green or not as to

the local character of the inherited peculiarity, there can at
least be no doubt that a morbid proclivity of tissue, predis-
posing its subjects to the development of malignant new
growths, is most frequently inherited — a morbid proclivity,
or constitutional peculiarity, which we cannot otherwise
regard or describe than as a diathesis ; and upon this con-
stitutional taint or vice the malignancy of these new growths
mainly depends. As to whether cancer is really hereditary
or not is a matter concerning which there is much difference
of opinion, but that it is occasionally so is proved by a case
of Dr. G. H. Barlow's, in which a lady was the fifth victim
to cancer of the liver in two generations. The deposits
which constitute new pathological growths, whether innocent,
malignant, or semi-malignant, are only so many evidences
of the differentiation of pathological processes in different
individuals ; for the predisposition may, in one set of
individuals, tend towards the production of tubercle, in that
of others to cancer, in others to fibroid tissue, and in others
to lardaceous matter : in each case there is an inherent
morbid proclivity to one or other of these pathological
processes, and in each this constitutes a malignant or
non-malignant diathesis, which may be perpetuated by
hereditary transmission.

The remaining diatheses may be dismissed in a few words,
not entirely because of their comparative, unimportance, but
because I feel that I have already dwelt sufficiently upon
these deviations from the norm which render individuals
different, in a pathological sense, from each other, and which
constitute an important element in their individuality. The
fact is that no enumeration of the diatheses can be complete,
as variation must differ in certainty and extent in proportion
to "the mingling of diatheses, and of all dispositions and

102'

liabilities to diseases in transmission from and through both
parents. The real point of practical importance is that we
should look for indications of the existence in the same
person of two or more morbid conditions or dispositions,
such as may be derived from both parents, or from several
ancestors, and suit our treatment accordingly."1 As in the
temperaments, so also in the diatheses, we seldom or never
meet with them in their ideally-perfect form or condition.
One may appear especially prominent, but when we recollect
and strive to appreciate the action and interaction of all the
causes which produce the individuality of man, we shall not
be surprised to find evidences of the mingling of diatheses
in every individual — an admixture as infinite in degree as in
variety.

Of the remaining diatheses, I may just mention the state
in which premature senility, as evidenced by such general
tissue-degenerations as atrophies, arcus senilis, white hair,
pale blood, and general failure of nutrition, amounts to a
disease : the heritable condition of skin associated with
certain affections, as psoriasis, eczema, acne and lupus ;
deficiency of nerve tone, which although not a diathesis in
itself, yet complicates them all; the hepatic diathesis, as
revealed by the subsequent appearance of xanthelasma
occurring in various parts of the body in an adult; the
diathesis denoted by chilblains, and that in which the
vascular system generally is very feeble, resulting in liability
to venous congestion in exposed and distant parts, even to
gangrene of the extremities.2

Such, at least, are some of the morbid proclivities
evidenced by patients in daily practice, and which are
potential agents in producing and maintaining man's indi-
1 Sir James Paget. 2 Mr. Jonathan Hutchinson.

io3

viduality by hereditary transmission. As Dr. Ord says : " In
that analysis of the Kpa<m of the individual which must
furnish the interpretation of much of his behaviour in
illness, the accurate estimation of many combined influences,
native and accessory, has been called the stumbling-block of
practice. It may better be called the touchstone of practical
skill. That physician does well who carries with him a
mental picture of some such perfect human animal as Galen
has imagined, and who marks on the diagram, with his
patient before him, the lines of original shortcoming, of
development, of warp, of injury, of degeneration, so as to
arrive at some clear sight of the outcome or resultant of all
in the present organisation and reactions of that patient."
In other words, that physician does best who most carefully
appreciates the physiological, psychological, and pathological
peculiarities of each of his patients — peculiarities which
render each patient different from any other, and which
constitute the elements of individuality in every atom of
humanity.

It should be distinctly understood, however, that such
predisposing causes of disease as temperaments and idio-
syncrasies— also those typical proclivities which I have just
considered under the term diatheses — however influential as
factors in modifying morbid processes in individuals, receive
their force and character from heredity, and may thus be
said to be merely effects of hereditary predisposition
specialised in certain sets of individuals : but hereditary
predisposition means far more than the temperaments,
idiosyncrasies, and diatheses, for it not only includes all
these, but also implies that a morbid predisposition which
has arisen in some individual, whether ancestral or parental,
has, by heredity, been transmitted to his offspring, and

104

either intensified by descent, or modified by age, sex, or
accessory circumstances. In speaking of diseases as heredi-
tary, we do not mean that the diseases themselves occurring
either in ancestors or parents are actually transmitted to
their offspring (who under those circumstances would be
born with them), but what is really meant is that a certain
organic constitution is inherited by the children, which
" being likely to undergo that pathological development in
the ordinary circumstances of life, is therefore described as
a constitutional predisposition or tendency to disease. We
do not in the least know what is the intimate nature of the
predisposition, but we know that it may be greater or less in
different persons, and that it is thought to be so great in the
cases of such diseases as epilepsy, phthisis, and insanity,
and so likely to be transmitted to children as to be a serious
objection, if not an actual bar, to marriage."1 At the same
time it should be remembered that the inheritance of a
disease-tendency, however likely, is not invariable ; for, as
Dr. Maudsley says, " One child may have it and another be
free from it. It is a very rare thing for all the children of
an insane parent to become insane ; indeed, it seems some-
times as if the child which falls a victim drains off the taint
for that generation, like a sort of scape-goat sent out into the
wilderness, so that the other children escape. Nay, more,
it sometimes happens that one child, aided by propitious
surroundings, collects, concentrates, and develops into some
form of genius the erratic forces which carry another child,
not so favoured by its circumstances, into the vagaries of
insanity. In like manner, it is not by any means certain
that all the children of a phthisical parent will have phthisis.
And, as regards epilepsy, although it runs in families in a

1 Dr. Maudsley.

very striking way, only one person perhaps in a generation
is struck by it. ... In all these cases, however, it is proper
to take due account of the before-mentioned fact, that a
disease-tendency which is latent or dormant at one period
of life, or throughout the whole life of the individual, may
undergo actual development at a particular physiological
epoch, or an occasion of a great bodily crisis from some
other cause (almost at the same time in twins, sometimes) ;
and that a tendency which is latent or dormant in one
generation may show itself actively in the next generation.
Herein we recognise the pathological parallel of the physio-
logical dormancy of qualities which was previously taken
notice of; disease-tendencies, like parental characters of
mind and body, are held in check or actually neutralised."

In approaching the consideration of those diseases in
which heredity is an especial factor, I purpose to allude
briefly to those diseases frequently occurring during uterine
existence, in the brief first stage of life of the unborn;
and, in the first place, it may be mentioned that some
writers make a distinction between what they term innate
diseases and those which are hereditary. The former may
be defined as those diseases with which neither of the
parents were affected, but were acquired by the foetus during
its stay in the uterus, in consequence of outward noxious
influences which operated upon it through the mother,
without creating in her a disease similar to that which
manifests itself in the child after its birth. These influ-
ences may be of a mechanical nature, such as pressure, a
thrust upon the pregnant uterus, or of a dynamic or
psychical kind. One or other of such influences, as also
bad regimen of the mother during pregnancy, is very likely
the cause of the so-called anomalies in the first formation,

io6

and of many others, which are founded upon an irregular,
perverted, or immoderately operating process of formation ;
also of all those anomalies which are commonly considered
as the consequences of the reception of a fright during
pregnancy, and which cannot entirely be denied ; lastly, of
all those different maladies which more recent authors
have discovered in the foetus, and with which the mother
herself was not affected.1 As we have already seen, the
individuality of every human being has its origin within
the womb of his mother, for here are enshrined not only
the mysteries of heredity, but also of that most potent
factor of individuality — variability, to which every atom of
humanity is subject. The phenomena of intra-uterine
morbid variability are almost as numerous as those trans-
mitted by heredity, and, curiously enough, many of them
may be present, whilst the mother may remain entirely
unaffected. Foremost amongst these individual morbid
modifications in the unborn may be mentioned those
dependent upon a perversion of the nutritive processes,
which may partake of the character of hypertrophy or
atrophy, and which may be general or local. Phenomena
of an inflammatory type may also occur — the inflammation
affecting the skin, the respiratory and intestinal mucous
membrane, also that of the eye-ball ; the serous membranes
likewise may undergo the inflammatory process, resulting,
according to its situation, in arachnitis, pericarditis, pleuritis,
or peritonitis; whilst the organic structure of the lungs,
kidneys, and thymus gland will sometimes be found to have
undergone inflammation.

Morbid phenomena, of the nature of effusions or exuda-
tions are also frequently met with during uterine existence,
1 Steinau.

and may consist of blood or of serum. Sanguinary
effusions have been found on the brain, in the lungs, and
also in the pleural cavity, whilst serous effusion has been
observed "between the membranes of the brain, into the
ventricles, into the spinal canal, into the peritoneal cavity,
into the cellular tissue beneath the skin, into the pelvis of
the kidney, and into the pericardium."1 Communicable
diseases, also, such as syphilis (in its gravest forms), small-
pox, measles, and scarlatina, have frequently been observed
during the uterine existence of children ; whilst, curiously
enough, in many instances, the unborn children have
suffered severely, although the mothers have been unaffected.
In like manner, new growths, both simple and malignant,
have become developed in unborn children when the
parents have shown no trace of them. Moreover, the
organs of children have been found, during uterine life,
deeply involved by tubercular deposit; hydatid cysts
have been found in the kidney, ascarides in the rectum,
and stone in the bladder. The foetal heart has been
discovered with its valves diseased ; arterial dilatation has
been observed, whilst limbs have been detected fractured,
and joints dislocated or anchylosed. Besides these active
forms of disease, the unborn are also subject to the whole
series of malformations, embracing the absence or over-
development of fingers or toes, webbed fingers, club-foot,
strabismus, abnormal growths of hair, skin marks, etc. ;
also to arrests of development in the eye, hand, leg, heart,
ear, or brain, and in those parts where a junction of medial
structures is required, and is not perfected, as in cleft-
palate, hare-lip, and spina bifida. Cyanosis, a malfor-
mation, owing to the opening that exists in the unborn
JDr. B. W. Richardson.

io8

between the right and left sides of the heart, in the auricles,
(and which should commence to close so soon as the child
commences to respire), remaining open, is a condition
sometimes, if not frequently observed.1

Such are but a few of the intra-uterine factors of
individuality, from which it will be seen that every unborn
child may have its health in after-life more or less
influenced by agencies to , which it is subjected within
the womb of its mother, independently of heredity, and
that natural variability which interacts with hereditary
predisposition. So refined, indeed, are the influences thus
exerted over the unborn, whilst in the maternal womb, that
every abnormal throb of her heart — every abnormal vibration
of her nervous system, is participated in by her unborn
child, whether harmfully or favourably, and may leave
impressions to which it may be subject during the entire
period of its existence. And thus we see that the differen-
tiation of individuals depends, not only on heredity
and co-existing variability, but may receive independent
impulses during uterine existence from agencies external
to, and beyond the sphere of both. These being in no
proper sense hereditary (although contributing to the
individuality of the children), I shall not now further refer
to them, but shall proceed, as briefly as possible, to consider
those diseases in which heredity is not only a potent, but an
essential element.

At the outset I may ask why is it that no two cases are
exactly alike in any disease ? And I, unhesitatingly, reply,
owing to variability in the original inherited strength, or the
acquired weakness of different organs and tissues. This
question and answer really contain my argument, as in a

1 Ibid.

109

nutshell, for I have already proved, over and over again, that
owing to heredity, natural variability, and the acquired
modifications wrought by external circumstances, every
individual differs from every other, not only physically, but
also mentally and morally, and that in every element of his
individuality. It is not, therefore, a fact that diseases —
even those of an acute or exanthematous form — differ, or
vary in their intensity beyond certain narrow limits, but that
the real difference or variation is in the individuals affected,
and the difference or variation extends not only to the
ultimate elements of his physiological and psychological life
— to bone, muscle, artery, vein, lymphatics, nerves, blood,
plasma, and organs, but also to the constitutional vigour or
feebleness — the natural power of endurance or intolerance —
in a word to the vital stamina and energy, which he can
summon to resist and overcome morbid processes when they
assail him. Disease, is, indeed, the lot of humanity ; but
every human unit differs essentially in his inherent and
acquired power of resisting and controlling it. Who that
has ever attended a family suffering from typhoid, scarlet
fever, diphtheria, small-pox, measles, or whooping cough,
has not witnessed the protean differences manifested in the
several individuals composing it, as to symptoms, intensity,
complications, sequelae, and convalescence? There is the
disease of a known character and quality, but how different
are its effects in the several members of the same family !
Can anyone say that the disease is different in each, or that
the intensity of the symptoms in some of them is dependent
upon a corresponding intensity of the virus ? Assuredly
not ; the real, rational, and only explanation of its different
manifestations must be sought and will be found in the
inherited and acquired constitutional differences in the

no

individuals affected. These differences, so marked even
amongst the children of the same parents, are naturally
more obvious amongst those having no kinship, as in the
case of unrelated individuals attacked by any of the diseases
named, or by erysipelas, pleurisy, pneumonia, acute rheu-
matism, bronchitis, influenza, or any other acute or chronic
disease ; we all recognise the differences every day of our
lives, but how comparatively few of the rank and file of the
profession regard them in their true light, and as dependent
upon the differences existing between man and man, in con-
sequence of the action and interaction of hereditary and
acquired influences. If we regard diseases as so many
entities of which we may all partake in different quantities,
and not as particular conditions — new phases of the vital
manifestations of the living body, whether of the nature of
functional derangements, or organic or textural degeneracy —
and which owe the differences of their symptoms, develop-
ment, intensity, and modes of termination to the inherited
and acquired constitutional differences existing between man
and man, we shall not only be following wrong principles in
practice, but prove unworthy of the trust committed to our
care — the health and well-being of our fellow men.

It must not, however, be understood or supposed that
I am anxious to try to prove that all diseases are alike
hereditary ; but it does seem to me but a natural sequence,
if we admit that, as I have indicated, every individual is
subject to heredity in his physical, mental, and moral con-
stitution, and to such an extent in his physical organisation
that the minutest structure of his every organ and tissue, is
characterised by it; that the life-history of his parents'
organs and tissues will be re-enacted, to some extent, at
least, in his own ; and that when they have developed

Ill

organic or tissue derangement or degeneracy of any kind, he
too will at least have inherited a predisposition to the same.
This I think may be accepted as a broad statement of a
general truth — the truthfulness of which is not assailed even
when we consider the effect of such modifying factors as
individual varieties of age, sex, and circumstances. The
constitutional weakness, whether local or general, or the
morbific predisposition transmitted by the parents may lie
dormant in one generation, but only to appear in the next ;
and the only exception I know to the inheritance by the
children of the morbid weaknesses and predispositions of
their parents' organs and tissues, is to be found in cases
where strains of weakness or disease in one parent are
neutralised by the excessive vigour and robustness of the
other. The laws of Nature are inexorable, and must be
obeyed ; yet conservative as she is in all her operations, she
preserves the characteristics of the race and family by
differentiating, within certain definite limits the individuals
composing each, so that notwithstanding this individual
differentiation, the race and family are perpetuated by
heredity, and thus in a general, as in a particular sense,
children resemble their parents, organically and dynamically?
in their constitutions, functions, and every attribute.

Whilst admitting that we are as yet unacquainted with all
the phenomena of disease that are transmitted by heredity,
those maladies or general morbid conditions generally con-
sidered to be, and admitted as hereditary, may be tabulated
as follows : —

I Gout, rheumatism, diabetes, scrofula,
tuberculosis, cancer, rickets, and
syphilis.

I Epilepsy, chorea, insanity, hypo-
chondriasis, neuralgia, apoplexy,
paralysis.

112

«(3) Physical[deformities and \

deficiencies of special > e.g.. Blindness, deafness, etc.
senses /

{Degeneration of vessels : fatty changes
in organs, loss of elasticity in the
skin. Premature greyness or bald-
ness, loss of teeth, and other signs
of decay.

(5) Some skin diseases, especially lepra and psoriasis.
<6) Emphysema and asthma.

(7) Gravel and urinary calculus.

(8) Haemorrhoids.

(9) Cretinism and albinism.
(10) Hernia.

(n) Icterus.
(12) Dropsy.

Hippocrates seems to have believed that almost all
diseases can become hereditary, judging from the following
quotation : — " Ex pituitoso pituitosus, ex bilioso biliosus
gignitur, ut ex tabido tabidus, et ex lienoso lienosus" etc.
This opinion was evidently adopted by the majority of early
physicians, and many even considered all fevers and inflam-
mations as hereditary. Day by day we are learning that
the hereditary proclivities of disease extend much further
than any list now usually accepted, and that a new line for
observation is thus indicated, which, industriously followed
out, promises to yield the most important results. Dr. B.
W. Richardson says : " The further my own investigations
extend — of the present, from experience and experiment :
of the past, from historical reading — the stronger is the
impression made upon my mind that the majority of the
phenomena of disease have a certain hereditariness of
character. For instance, that phenomenon which we call
intermittent action of the heart, I have found to be distinctly
hereditary. I have seen a child who exhibited it at the
moment of birth, and to whom it was traceable through two

generations. The phenomenon in this case, nervous in
character, is induced purely by mental shocks acting defi-
nitely, but in so refined a manner, on the heart, that we as
yet know nothing of the physical change that is developed
in the nervous matter. Again, I have known families in
whom the tendency to some forms of communicable disease
has been markedly apparent, and I have known instances of
the reverse. Thus I have seen hereditary proclivity to
scarlet fever and to diphtheria. I have also seen, in respect
to one of these diseases (scarlet fever) hereditary opposition
to it, if the term be allowable."

There can at least be no doubt that peculiarities of
formation, and the tendency to particular affections, are
transmitted in families from one generation to another ; so
that in one family will be recognised a peculiar form of the
head, predisposing to inflammation of the brain, madness,
epilepsy, paralysis, apoplexy, etc. ; in a second family may be
found a remarkable formation of the chest, leading to con-
sumption ; in a third family may be found a peculiarity of
structure, predisposing to disorders and diseases of the
heart ; in a fourth an innate tendency to derangement or
disease of the stomach, liver, and bowels ; and in a fifth a
predisposition to diseases of the skin ; whilst in large families
it may be found that some of the members have been prone
to affections of certain organs, from generation to generation.
These hereditary physical peculiarities are sometimes con-
nected with peculiar conditions of the nervous system, but
more frequently of the capillary portion of the circulatory
system.

Discarding all accepted lists of hereditary diseases as
such, I now propose to pass in rapid review the principal
diseases of the human body, in connection with the organic

n4

-systems of which it consists, for the purpose of observing
how far, or to what extent, they are subject to the influence
of heredity, and how far this influence bears upon indi-
viduality as affecting disease. First, with regard to

Diseases of the Circulatory System. — Are these, or any
of them, subject to heredity? Before this question is
answered, it should be carefully borne in mind that the
whole subject of disease tendencies and immunities in
connection with heredity has been before the public and
the profession for comparatively few years, and if I were
to sum up our present knowledge of the heredity of these
diseases, and reply in the negative, I fear my answer would
savour more of ignorance than of scientific exactitude;
for to say that things are not, when they may be, is surely
presumptive of self-contented ignorance, and in direct
opposition to the spirit of scientific inquiry and progress.
Thus while circumstances may compel us to confess our
ignorance, science is ever beckoning us on, and promising
us increased knowledge and deeper lore if we only follow
her aright. Synthetically we find man's physical, mental,
and moral nature not only subject to, but to a great extent
dependent upon heredity, and analytically we find all his
•organs and tissues subject to the same influence; and if
such is the case in health, why should it not be so in disease
— since diseases are simply new phases of the vital manifes-
tations, partaking of the character of either functional
derangement, or organic or textural degeneracy ? And if so
in some diseases, as it undoubtedly is, why not in all, as they
are merely deranged functions, or organic or textural
degenerations of organs or tissues which are unquestionably
inherited? It is admitted that man, in all his parts and
functions, is the result of heredity, with the exception of the

modifications effected by external circumstances ; nay,
more, his constitutional vigour or weakness is, originally,
due to the same cause ; also that he bears within him certain
morbid tendencies which have been transmitted to him. Is
it not therefore evident that the morbid conditions which
afflict him must be due either to nature working within him,
or circumstances working upon him from without ? And if
it is conceded that his physical nature and parts are
originally the result of heredity — that his constitutional
vigour or power of resistance is originally due to the same
cause, and that circumstances may develop inherent weak-
ness of tissue or organ, I ask for' nothing more, only that
if certain tissues or organs in the body are predisposed to
disease in consequence of heredity, it should be admitted
that all may be, and probably are ; and if such be the case
in brain and lung, why not also in heart, artery, and vein ?

Coming more closely to consider the diseases and
anomalies of the circulatory system, I may ask, if it is
admitted, as it is, that the quality of a man's bones, muscles,
and organs is undoubtedly inherited, why should the heart-
muscle and the blood-vessels be excepted? And if it is
proved, as it is, that certain inherent weaknesses of certain
organs and tissues manifest a predisposition which cir-
cumstances may develop into disease, why should the heart
and blood-vessels be exempt from inherent weaknesses
of structure, which may in like manner predispose them to
disease? Without following this argument further, there
can at least be no doubt that physiological functions are
modified by anatomical structure in health as in disease,
and thus the physiological functions of the circulatory
system will be more or less modified by the structure of
the heart, arteries, and veins, whether hereditary or acquired,

n6

in any individual. For the present I do not consider it
necessary to refer to congenital diseases of the heart,
such as abnormal positions, congenital narrowness
and closure of the ostia of the right side, stenosis and
atresia of the pulmonary artery, with closure of the septum,
stenosis of the right conus arteriosus, with an opening in
the inter-ventricular septum, simple stenosis and atresia of
the pulmonary artery with an opening in the ventricular
septum, etc., my object being to demonstrate, not that
certain diseases of the heart are congenital, but that,,
owing to heredity, variability, and accessory circumstances,
the organs, vessels, and tissues of every human subject are
so variously differentiated by individuality, that they are as
variously predisposed to morbid influences, whether of the
nature of adynamia, functional derangement, or structural
degeneration. Temperament, idiosyncrasy, and diathesis
are more or less involved in every question concerning the
comparative health of individuals, but we mnst dig down
deeper into the origin of constitutions if we are anxious to
account for differentiation, which is as universal as humanity
itself; and thus we find in the strongest and healthiest, as
well as in the weak and invalidish, that in certain organs,
vessels, or tissues, there is a predisposition to certain
functional or structural alterations, which render their
subjects, in varying degrees, liable to morbid influences,
referable either to atony or adynamia, impaired functional
activity, or structural degeneration. From this view let
me now briefly inquire as to how individuality of tissue
predisposes to diseases of the heart and circulatory system
in general. Weakness, like the term disease, is only a
comparative term, and, like the latter, it admits of infinite
gradations or degrees. Inherent weakness of the circu-

latory system is the parent of many evils, and may evidence
itself in many ways. The hollow, propelling muscle — the
heart itself— may inherently lack the necessary vigour and
tone indispensable for the normal discharge of its functions,
the coats of the arteries and veins may likewise be inherently
deficient in tonicity, and the blood itself may be deficient in
quality and quantity. How protean are the effects of such
causes, and how infinite are the degrees in which individuals
may be affected by them ! And yet in proportion to the
degree of cardiac or vascular inherited weakness, and in
proportion to the quality and quantity of the circulatory
fluid, will the individuals so affected be subject to the functional
derangement or textural degenerations to which these in-
herent deficiencies predispose. Syncope, palpitation, inter-
mittent action of the heart, angina pectoris, neuralgia cordis,
cardiac spasm, oedema, chilblains, and the whole range of
affections involving the complexion, from sthenic plethora
to asthenic anoemia, are but a few of the morbid conditions
resulting from functional derangement of the heart and its
vessels, or of the vascular supply; and to these may be
added the various affections originating from vaso-motor and
vaso-inhibitory derangement of arteries, and from thickened,
weakened, contracted, or dilated vessels generally.

Roughly estimating the causes of diseases of the heart
and the general circulatory system, they may be said to
consist in inflammation — acute or chronic — hypertrophy,
atrophy, dilatation — of such forms of structural degeneration
as the fatty, calcareous, and amyloid, and of neoplasmata,
such as the carcinomatous, tubercular, syphilitic, and parasitic.
Are all individuals equally, subject to these, and if not, why
not? Simply because the cardiac and vascular tissues of
many individuals are insusceptible, whilst others are, more

H

u8

or less, particularly susceptible ; and in other cases the cir-
cumstances of their life-history have either developed in-
herited predispositions, or originated them de novo, to be
passed on to future generations. Let us take, as an example
of the inflammatory causes, acute diptheritic or subacute
verrucose endocarditis. What are the facts known as
to their etiology? Simply that one or both are usually
associated with rheumatic arthritis, childbirth, or pregnancy,
and occasionally with the acute exanthematous diseases.
How many thousands of such conditions occur without the
slightest implication of the endocardium at all ? And why
should pericarditis be far more frequently associated with the
gonorrhceal form of rheumatism than the endocardial form
of inflammation ? Why, also, with regard to prognosis in
the chronic and sclerotic form, are as many individual pecu-
liarities produced by the diseases of the different valves as
there are individuals affected ? Is the disease itself different
in every individual ? Assuredly not ; but the real reason is
that while the individuality of tissue in some predisposes
them to such affections, in the majority of others it renders
them insusceptible. So also with regard to degenerative
changes in the cardiac or vascular tissues, whether fatty, cal-
careous, amyloid, tubercular, or syphilitic. We shall in every
case find the result originating either in hereditary or acquired
predisposition, or in both combined, and in every case the
proportionate action of these factors is as different as are its
results in different individuals. For hundreds who have
suffered from heart affections of various kinds, and in different
degrees, there are thousands and thousands who, during
long lives, have neither experienced inconvenience nor
derangement of any kind in connection with their circulatory
system, and this exemption has been entirely owing to the

U9

fact that neither their ancestors or parents, nor the circum-
stances of their own lives, have tended to produce or develop
such conditions. This is a fact which, though recognised,
is far too often lost sight of in diagnosing the actual condition
of patients, as the knowledge thus gained of their individ-
uality as exemplified by their predispositions, vital energy
and endurance, so far as they can be estimated, is of far
greater importance than any mere physical diagnosis, how-
ever exact, for whilst the latter, as Dr. Milner Fothergill says,
may be a mere series of barren facts, the former mode is
pregnant with potential hypotheses. Whilst it is obvious
that these hereditary predispositions to particular diseases or
morbid conditions cannot be quite neutralised or removed
by medical art, yet if we also know, and can, by any means,
obviate, the immediate agents which are the causes of these
diseases, we may often do much towards their ultimate
prevention.1

Are cardiac or vascular diseases heritable as such? I
think I may safely reply in the affirmative : at least there
can be no doubt that the organic or textural peculiarities
which predispose to them are unquestionably transmitted
from parents to their child or children. As I have already
said, however, the entire subject is so comparatively new,
and this particular question has received so comparatively
little detailed attention, that the facts in support of an
affirmative reply are not so numerous as they might other-
wise have been. There is at least one case recorded by
Lancissius, who says that he saw an enlargement of the
right heart in a man whose father, grandfather, and great-
grandfather were all known to have had the same abnormal
structure of this organ. My friend, Dr. Ernest Sansom,
1 Dr. G. H. Barlow.

120

has also informed me of a case of a young man, in whom
enuresis was complicated with aortic valvular mischief,
which he had undoubtedly inherited from his father, who
suffered from precisely the same complication!1 I have
myself witnessed cases in which intermittent action of the
heart had been transmitted through several generations —
also others of epistaxis, and abnormal distribution of the
radial artery, which had been similarly transmitted. The
almost specific hereditariness of haemophilia has already
been referred to, and it is an acknowledged fact that
varicose conditions of the veins are so hereditary, that the
predisposition has been regarded as forming a diathesis.
Nothnagel, in estimating the etiology of cerebral hyperaemia,
includes heredity as one of the factors of its production ;
at least, he admits the hereditariness of the apoplectic
habit, and what he terms " plethora universalis," of which
cerebral hyperaemia is only a symptom. There can be
little doubt, also, that the degenerative vascular changes
generally associated with senility, whether of the nature
of miliary aneurisms (Bouchard), or fatty, or atheromatous
deposits, and which Dr. Chepmell has graphically described
as " rotten vessels," are very frequently if not invariably
transmitted; at any rate, it must be admitted that the
apoplectic habit, and consequently apoplexy, characterises
certain families for generation after generation, and it is
surely fair to deduce from these facts that a strong tendency
to such vascular changes is assuredly inherited. What I am
especially anxious to enforce is, that however potent cir-
cumstances may be in the development of disease, there is
invariably a pre-existing disposition in every individual,
which is as personal as his features or character, and which
in every case will give a certain bias or tendency to the
1 The distinguished Arnold family affords several examples.

121

morbid processes by which he may be assailed during his
existence ; and the practical outcome of the due recognition
of this fact will be that every patient will cease to be regarded
as a mere animated machine like each of his fellows, and be
appreciated as a man, in his microcosm, and as differing not
only in form and feature from every other man, but also in
temperament and diathesis, and in everything that concerns
his predisposition towards morbid processes. Portal has
justly observed, that in the treatment of patients whose
ancestors are known to have died of some interior organic
defect, we always ought to presume the possibility of the
existence of a similar defect; and, if the diagnosis be
doubtful, we should, by a strict investigation, endeavour to
find out whether our apprehension be well-founded or not.
How all-important therefore is an intimate knowledge of the
life-history of every individual, before we can diagnose his
real condition, and treat him accordingly.

Diseases of the Nervous System. Not one alone, but
several volumes might be written in discussing the diseases
of the nervous system as affected by individuality. In the
few pages at my disposal, I hope, however, to make it
clear that owing to heredity, and natural or acquired
variability they are all more or less subject to its influence.
Indeed, so fully is this recognised that it has been alleged
that the mysteries of hereditary transmission are pent up in
the nervous system, and that the hereditary phenomena
of disease are due to modifications in nervous matter.
But how these modifications "pass from the parent to the
offspring, and that, too, by paternal as well as by maternal
line, is simple mystery, on which science merely speaks as
yet to tell us that the fact must be accepted."1 In the
1 Dr. B. W. Richardson.

122

course of the foregoing pages I have endeavoured to prove
that the brain and nervous system are anatomically,
physiologically, and psychologically transmitted by heredity ;
in other words that, organically and dynamically, the structure,
functions, and powers of the human brain and nervous
system are hereditarily transmitted from parents to their
children. Of this fact there can be little or no doubt ; but
I have now to consider whether this statement is true in a
pathological sense, whether in fact the scientific accuracy of
the first statement does not involve an affirmative reply to the
question : Are the derangements and diseases of the brain
and nervous system subject, in like manner, to the law of
heredity ? In attempting to answer this question I propose,
in the first place, to refer in a few words to those derange-
ments or diseases of the brain grouped under the term morbid
psychological heredity, and including Hallucination, Mono-
mania, Suicide, Mania, Dementia, and Idiocy, and assume
that there is no form of mental disease independent of an
organic cause, for "since the direct cause of insanity is some
morbid affection of the nervous system, and as every part of
the organism is transmissible, clearly the heredity of mental
affections is the rule."1

Esquirol observes, that, of all diseases, insanity is the
most hereditary, and reliable statistics prove that it is so to the
extent of from thirty-five to fifty per cent. All the forms
and varieties of insanity are unquestionably transmissible by
heredity, and nothing could be easier than to supply facts
and cases in illustration and defence of this statement, but I
shall content myself by quoting the following from the
graceful pen of Dr. Maudsley concerning the hereditariness
of suicide. He says : — "It is, indeed, striking and startling
iRibot

123

to observe how strong the suicidal bent is apt to be in those
who have inherited it, and how seemingly trivial a cause will
stir it into action. Persons afflicted by it will sometimes
put an end to themselves on the occasion of a petty
contrariety, or when they are a little out of sorts, and with
almost as little concern as if they were only taking a short
journey. Public feeling is much shocked, as if something
very unnatural had happened, when a child of eight or nine
years of age commits suicide, and is prone to rush to the
hasty conclusion that so fearful an act would never have
been done by so young a child unless it had been subjected
to very cruel treatment. The real truth commonly is that
the act is done for a cause that seems utterly inadequate ,
perhaps because his master inflicted a slight punishment,
or because his father scolded him, or because his mother
refused to let him go to a school-treat But if the child's
family history be inquired into, it will usually be found that
a line of suicide, or of melancholic depression with suicidal
tendency, runs through it. So it comes to pass that a slight
cause of vexation is sufficient to strike and make vibrate the
fundamental life-sick note of its nature." Many examples
might readily be given in support of these facts, and many
more in connection with the heredity of hallucination,
monomania, mania, dementia, and idiocy, but I can now
only refer the reader to the works of Brierre de Boismont,
Esquirol, Moreau, Maudsley, Tre'lat, and other writers on
the subject, in which will be found innumerable instances of
the heredity of every known form of insanity.

I must now consider, as briefly as possible, those very
interesting phenomena denominated metamorphoses or trans-
formations in transmission, which occur not only between
generation and generation, but frequently also in the same

124

individual. These have been regarded as exceptions to the
law of heredity, inasmuch as like in these cases can scarcely
be said to produce like, but, as Ribot says, "We are
anxious always to keep in view the important truth that
there is never a total exception to heredity — the exceptions
to it never going beyond the individual characteristics ; " so
that we may regard these metamorphoses in transmission
not so much as exceptions to the law of heredity — not so
much as differences in kind as differences in degree, charac-
terising certain individuals in consequence of the law of
variability. To make plain what is meant by these meta-
morphoses in transmission, I may state that nervous affections
are often so transformed. Those parents who have suffered
from convulsions may have the predisposition inherited from
them by their children changed into hysteria or epilepsy.
A case is recorded where " hyperoesthesia in the father
branched out in the grandchildren into the various forms of
monomania, mania, hypochondria, hysteria, epilepsy, con-
vulsions, spasms," in fact nothing is commoner than " to see
simple insanity become suicidal mania, or suicidal mania
become simple insanity, alcoholism, or hypochondria." It
would be very easy to give numerous examples of these
metamorphoses taken from pathology and history, but for a
detailed account of these most interesting phenomena I
must refer the reader to the Psychologie Morbide of Dr.
Moreau, of Tours, from which I have already quoted. He
will there find that " the lypemania of parents may become
in their children a tendency to suicide, insanity becomes
convulsions or epilepsy, scrofula is replaced by rickets, and
vice versd." As Ribot continues : " Fixed ideas in the pro-
genitors may become in the descendants melancholy, taste
ibr meditation, aptitude for the exact sciences, energy of will,

125

etc. ; the mania of progenitors may be changed in the
descendants into aptitude for the arts, liveliness of imagina-
tion, quickness of mind, inconstancy in design, sudden and
variable will." "Just as real insanity," says Moreau, of
Tours, " may be hereditarily reproduced only under the form
of eccentricity — may be transmitted from progenitors to
descendants only in modified form, and in more or less
mitigated character — so a state of simple eccentricity in the
parents, a state which is no more than a peculiarity or a
strangeness of character, may in the children be the origin
of true insanity. Thus in these transformations of heredity
we sometimes have the germ attaining its maximum intensity ;
and, again, a maximum of activity may revert to the mini-
mum." It should also be remembered that as in certain
families, so also in certain individuals, two or more morbid
predispositions may be found to co-exist ; thus it is not
unusual to find such diseases as acute mania, epilepsy, and
phthisis in children of one family, and the frequent appear-
ance of cancer, as well as scrofula in families predisposed to
insanity has also been observed ; in fact, Sir William Gull,
in his address at the meeting of the British Medical Asso-
ciation, at Oxford, said that scrofulous children were not
uncommonly the offspring of parents who had had cancer.
So also in individuals it is no unfrequent occurrence to see
phthisis followed by acute mania, religious mania succeeded
by phthisis, scrofula followed by suicidal melancholia, psoriasis
succeeded by acute mania — gout followed by insanity — gout
succeeded by carbuncle, etc. That there is a strong here-
ditary element in all these cases cannot be denied, so that as
has been observed, it behoves us to look out for indications
of the existence in the same person of two or more morbid
conditions or dispositions, such as may be derived from both
parents or from several ancestors.

126

In seeking to account for these metamorphoses in trans-
mission, occurring as they do, not only between generation
and generation, but also frequently in the same individual,
various physiologists have given as diverse- opinions ; some
regarding them simply as exceptions to the law of heredity ;
others, as the result of a law of spontaneity, acting reci-
procally with heredity ; others, again, as the result of both
parents presenting the same characteristics, when heredity
may acquire such power as to destroy itself. In following
out my argument, however, I contend that these metamor-
phoses are simply the natural phenomena of the law of
variability to which every individual is subject, and which
is the fundamental element in his individuality. Heredity,
we have seen, is the ideal, but unattainable law ; for Nature
preserves the type or species not by simply reproducing
the parents in the children in a monotonous succession,
but by varying each individual within certain limits, so that
no two individuals who have ever existed have been precisely
alike. This fact, to which I have already alluded more
than once, is to my mind a conclusive proof that these
transformations in transmission are the result of the law of
variability interacting with that of heredity ; for this varia-
bility of individuals extends to their whole nature — phy-
siological and psychological; and if so, why not also to
those morbid predispositions which we include under the
term pathological, since all are inherited in various degrees,
varying with the individual. For example, let us suppose a
man of nervous temperament marrying with a woman
who has suffered from hysteria ; their offspring will to some
extent resemble one or both physically, mentally, and
morally ; but deeper down in the constitutions which they
have inherited dwell potentialities capable of producing

I27

epilepsy, alcoholism, hypochondriasis, mania in its every
form — of ringing the changes upon the whole series of
nervous disorders, and perpetuating them — unless neutralised
by judicious inter-marriages, from generation to generation.
No two individuals in any family or generation will be
precisely alike any other physically, mentally, morally, or
morbidly, but each will, cceteris paribus, have inherited in
various degrees a predisposition to neuropathic conditions
resulting from molecular morbific instability in the nervous
systems of their parents or ancestors. So likewise, to what
disastrous results may the union of a pair respectively
gouty and scrofulous not lead ? Gout, scrofula, tuberculosis
in its protean forms, Bright's disease, heart diseases,
haemophilia, cancer, rheumatism, chorea, apoplexy, and
the whole host of dyspeptic troubles ! These are but a
few of the gross results, yet each individual involved will
differ in the quantity and quality of his morbid heritage
from every other, and it is thus, and thus, and thus, that
I think the so-called metamorphoses in transmission may
be satisfactorily accounted for. To sum up : heredity is
the law, but the co-existing and interacting law of varia-
bility necessitates the differentiation of individuals; and
so I regard these transformations in transmission not so
much as differences in kind as differences in degree of
inheritance affecting certain individuals, and that these
degrees may be of the nature of development or neutrali-
sation, />., either an increase or decrease of the primary
heritage according to the circumstances. As to how these
metamorphoses occur, science is as yet silent : we have
only to deal with natural phenomena, and to interpret
them as best we may. As Ribot says: "We cannot tell
why a given mode of psychic activity is transformed in

128

process of transmission, nor why it assumes one form
rather than another. Were the solution of the problem
attainable, it would doubtless reveal some singular mys-
teries In truth, we can only ascertain facts ; but

this is quite enough, since the facts show by what concur-
rence of fortuitous circumstances and accidental causes
nature produces diversity."

But to return to the consideration of heredity in connec-
tion with nervous diseases. It must be conceded that
heredity predisposes mankind not only to such diseases as
epilepsy and insanity, but to peculiarities in the mode in
which man is affected by minor ailments. For example,
how frequently do we recognise a predisposition to cephalalgia
in those families whose inheritance seems to have especially
influenced the nervous system ; also to dyspeptic troubles,
involving nausea, vomiting, and diarrhoea, and to the
manifold affections usually regarded as disturbances in the
vaso-motor system ? Not only so, but it is a well-known fact
that the members of certain families will live into old age,
however they may have subjected themselves, or been subjected
to pernicious influences during their lives; and notwithstanding
their being thus handicapped in the struggle for existence,
will contrast most favourably with those who apparently have
lived simply, carefully, and well. In connection with here-
ditary predisposition to diseases of the nervous system, Dr.
W. B. Carpenter says : "The fact seems to be that the nervous
system is so peculiarly liable to be shaped and modified by the
mode in which it is habitually called into exercise, that it
takes on a particular abnormal form of activity far more
readily than any other organ ; and thus, when a special form
of malnutrition has once established itself, this may be
transmitted to the offspring without the prolonged action of

I2Q

its special factor through many successive generations."
That acquired predispositions tend to produce themselves in
the offspring is proved by the fact, evidenced by the same
authority, that the effect of habitual alcoholic excess
not only produces a tendency to insanity in the subject of
it, but also engenders in the offspring (especially when both
parents are drunkards) a disordered state of brain-nutrition,
which may express itself in idiocy, epilepsy, alcoholic
craving, mental instability , weakness of will, incontrollable
hysteria, and the like, as well as insanity. And the same
may be said of abnormal moral habits, which, when they
have fixed themselves in the cerebral organism, tend to
reproduce themselves in succeeding generations, as we see
in hereditary kleptomania.

Dr. Bastian says : " It is now a well-established fact
that persons who are endowed with a neurotic habit of
body, very frequently transmit a similar tendency to their
children. It is not a tendency to any one particular disease,
but a vulnerability of the nervous system as a whole which
is transmitted, so that under the influence of even a
•comparatively slight strain, this weakness may manifest itself
in one or other of various ways. It may reveal itself
by mere general nervousness or tremors, by attacks
of chorea, by epilepsy, or by one or other of the forms
of insanity." This quotation refers to the now well-
established neuropathic predisposition, which may be either
inherited or acquired, and which is a factor of prime
importance in the etiology of such neuroses as the psychoses,
chorea, epilepsy, hysteria, hypochondriasis, etc. By this
term we understand a pathological constitution affecting the
functional activity of the nervous system (Griesinger), in
consequence of which those subject to its influence
exhibit throughout their lives the utmost variety of symp-

130

toms in connection with pathological processes, whether
sensory, motor, or psychical. Science has as yet nothing
to say as to the real nature of this peculiar anomaly ; and
however some may seek to account for it by the aid of
"delicate trophic disturbances," or "modifications of
molecular arrangement " — hypotheses so vague and useless
as to explain nothing — we can only console ourselves with
the fact that such constitutional neuropathies really exist,
and that future researches will, it is to be hoped, throw
some light upon a question which is at present inscrutable.1
Professor Erb, in referring to the hereditary neuropathic
predisposition, describes it as "that unfortunate condition:
which forms the inheritance of so many families, in which
the most diverse forms of neurosis are, so to speak, innate,,
and propagate themselves from one generation to another,
sometimes affecting chiefly the psychical, sometimes the
sensory, and sometimes the motor and vaso-motor regions of
the nervous system. To it many forms of neuralgia owe
their origin. Anstie, who has paid particular attention to this
neuropathic hereditary predisposition, attributes to it not only
a predisposition to psychoses, epilepsy, chorea, hysteria,
paralysis, etc., but also to phthisis, and states that in eighty-
three cases of neuralgia investigated with regard to this
point, he found there were seventy-one in which such a
family predisposition existed, and of these, fifty-three cases
occurred in neuropathic, and eighteen in phthisical families.
In such cases the coincidence of neuralgia with other neu-
roses, or its alternation with epilepsy, various psychoses,
migraine, etc., is not unfrequently observed. This hereditary
origin of neuralgia is of course most obvious in the not unfre-
quent cases where there is a direct hereditary transmission
1 Ziemssen.

from the parents to the children, where the father or mother
has suffered from neuralgia, and the child has likewise been
subject to it." This condition, whilst necessarily associated,
must not be confounded with the nervous temperament from
which it differs materially : inasmuch as mere temperament in-
volves in itself no morbific predisposition, whereas the former
is essentially neuropathic, and signifies that every atom and
molecule of the nervous system bears upon it the impress
of a pathological condition which is inherited and indelible.
It might indeed be regarded as a nervous diathesis, which
it really is. There are also certain constitutions of mind
which are not only peculiar in themselves, but which
predispose to nervous affections, and are capable of being
perpetuated by heredity. Thus in one family one may find
but little irritability or sensibility 'prevailing, so that each
member may be compared to a "lake sunk between two
hills — the wind and the storm may pass over it and not
ripple its surface. In another family one finds a high degree
of irritability and sensibility prevailing, so that one of its
members may be compared to a delicate tree planted on
some mountain top — blown about by every breath of wind —
bent before the slightest breeze, the rude blast tears it up
by the roots, and it withers ! " x Well, indeed, may we regard
Man as the sublimest and most wonderful being in the
universe, for in every element of his microcosm, each
human being differs essentially from each other, and as in
health, so likewise in disease !

Amongst those nervous diseases, a predisposition to-
which is undoubtedly inherited, I shall instance, in the first
place, hysteria. So important is this predisposition as a
cause of hysteria that it is capable of developing not only a
tendency or liability to it, but also the complete evolution of
1 Armstrong.

the disease itself; whilst the hysteria of parents or ancestors
usually predisposes to hysteria in the children — thus
denoting an inheritance of like tendencies, and especially in
transmission from mother to daughter. Various other ner-
vous affections, which have appeared in the ancestors, favour
a disposition to hysteria in the descendants ; just as it
happens, on the other hand, that hysteria appears in one
generation, and epilepsy, chorea, insanity in the next.
Briquet has proved that more than a fourth of the female
descendants of the hysterical suffer in their turn from
hysteria ; and Amann has recently stated that in 208 cases
of hysteria he proved with certainty an hereditary tendency
165 times — that is in seventy-six per cent. All those pheno-
mena which indicate the possession of a neuropathic predis-
position have a decided influence upon the transmission of
a tendency to hysteria : moreover, privation, insufficient
nourishment, debility in the parents arising from senility;
or chronic diseases, as phthisis, apparently favour the
development of a tendency to hysteria in the children. The
inherited tendency to hysteria may for a long time remain
latent, until, in fact, some constitutional shock or epoch
developes an outbreak of the disease. In other cases the
transmitted predisposition may be strong and effective
enough to develop it independently. It should, however, be
remembered that in a few cases hysteria may result in a
child from the mere fact of its imitating an hysterical parent.
That weakly constitutions manifest a greater predisposition,
must be conceded, just as acquired conditions of debility
favour the development of the disease. Herein is probably
to be found the connecting link in those cases in which
debility of the parent induces hysteria in the descendants.1 ,
1 Jolly. — Ziemssen, vol. xiv.

133

Epilepsy. — The hereditariness of a predisposition to this
affection is beyond all doubt, as is acknowledged by every
authority who has written upon it. The predisposition itself
may be transmitted directly from parent to child, or it may
remain latent in a generation or two, and appear in the
grandchild or great-grandchild \ moreover, it may be trace-
able only in the collateral branches of the ancestry, as in
hereditary maladies. Predisposition may also be connected
with congenital formation, as is often evidenced in cases of
chronic hydrocephalus, also in those in which there is a
misshapen or unsymmetrical form of the head. Amongst
other predisposing causes may be mentioned the scrofulous
diathesis and idiosyncrasy ; also the epochs of childhood
and puberty, at which periods the nervous and muscular
systems attain their maximum of sensibility and irritability,
and the physical susceptibility is greatest. With regard to
the influence of the scrofulous diathesis, Dr. Cheyne holds
that epilepsy is as certain a manifestation of the strumous
disposition as tubercular consumption, or psoas abscess ; but
it may be observed that the strumous diathesis, and a parti-
cular conformation of the head, are both very likely to
descend from parents to their children.1 In those cases of
epilepsy which are hereditary, the affection is usually
developed at an earlier age. In the great majority of cases
epilepsy is developed between ten and twenty years of age,
and especially at or about the period of puberty. According
to Echeverria, the occurrence of the symptoms of hereditary
epilepsy is before puberty ; according to Reynolds, not later
than the twentieth year. It may, therefore, be assumed that
an individual with an hereditary predisposition, remaining
healthy up to the twentieth year, will also escape epilepsy

i Watson.

after that time, so far as its development is excited by the here-
ditary tendency alone. Such individuals often suffer from
eclampsia as early as during the first dentition, but afterwards
again remain apparently healthy up to the outbreak of the
epilepsy.1 Although the father or mother of the patient
may never have had an attack, either of the grandparents,
or uncles or aunts may have been subject to it. Zacutus
Lusitanus mentions the case of an epileptic man who had
eight children and three grandchildren afflicted by the
disease. Stahl and Reininger adduce instances of the whole
of the members of a family being attacked by it at the period
of puberty. Boerhaave remarks that, like several other
hereditary maladies, it often passes over alternate generations,
and he adduces an instance in which all the children of an
epileptic father died of it. Dr. Copland says : " I had, in
1820, a brother and sister some time under my care, who
inherited the disease from their father, and they had two
other brothers and one sister also subject to it — in all five.
The fits appeared in all of them about the period of puberty,
and one of the brothers died about the age of forty from
apoplexy, complicated with the seizure. MM. Boucher and
Casauvieilh state, than in no patients, respecting whom they
had made inquiry, 31 were hereditary cases ; and M. Esquirol
found, that in 321 cases of epileptic insanity, 105 were
descended from either epileptic or insane parents."

Amongst those cases in which the disease is produced by
factors of a kind not appreciable anatomically, which at times
affect the nervous system alone, at others the whole organism,
inherited predisposition or tendency occupies the first place,
and is of prime importance. Seeing that all observers are
agreed upon this fact, I need not further cite either statistics
1 Nothnagel.

or instances in its defence, although in addition to those
already quoted, I may be permitted to mention the experience
of Echeverria, who, out of 306 patients under his own care,
had observed 80 with an hereditary tendency. With regard
to this hereditary tendency to epilepsy, we must be careful
not to limit it too much in its signification, as, for example,
in assuming that epilepsy only and strictly in the forbears is
calculated as strictly to reproduce epilepsy in the children.
This view cannot be upheld for a moment, as owing to those
phenomena of the law of variability which I have already
referred to, and which are denominated metamorphoses in
transmission (by which also the differentiation of individuals
is necessitated and secured) it by no means follows that the
ancestral or parental form of affection is strictly inherited by,
or transmitted to the children, but that whilst similar in
kind, it may be very different in degree. As Professor
Nothnagel, of Jena, says : " The children of those parents
may become epileptic who have been mentally diseased, but
who have never suffered from convulsive affections. The
fact is, hereditary disposition must be taken in a far broader
sense, and the proposition may be enunciated that any
neurosis in the parents, whether it be of a lighter or more
serious kind, may plant in the children the germ which
may develop into epilepsy. This obtains not only in regard
to hysteria, hypochondria, and catalepsy, but I have observed
cases where — e.g., the mother suffered for many years from
pronounced migraine, .and with this exception there was
absolutely nothing else in the way of family tendency to be
found, and yet a daughter was hysterical, and a son epileptic.
From my experience, I am even inclined to ascribe to
neuralgia of many years' standing in the parents, a capacity
of producing epilepsy in the children. There are even not

wanting instances where, in connection with a mere 'nervous-
ness ' of the ancestors, epilepsy made its appearance in the
descendants."

I have already stated that in hereditary epilepsy the first
occurrence of its symptoms is, according to Reynolds, not
later than the twentieth year ; and to this I may now add
that an individual who has inherited a predisposition to
epilepsy may escape its development altogether if his general
health remains satisfactory up to this period. This latter
statement depends, of course, upon the assumption that the
attack is produced entirely as the result of the inherited pre-
disposition, and does not affect the occurrence of epileptic
seizures from other causes. Although epilepsy may be
caused by many factors, such as alcoholic and sexual excesses,
prolonged mental strain, disturbances of nutrition, as pro-
duced by defective nourishment etc. ; external injuries, etc.,
yet none of these are so effective in exciting " the central
epileptic change" as hereditary predisposition. Why this
inherited tendency should be so much more active during
youth — from the seventh to the seventeenth year — we really
cannot satisfactorily explain, notwithstanding the many
theories which have been propounded to account for it : we
can only at present accept the fact, and trust that time may
throw some further light upon this interesting question in the
future. With regard to prognosis, Reynolds maintains that
those cases are least amenable to treatment in which the
source of the disease is involved in the greatest obscurity.

Chorea. — As in hysteria, epilepsy, etc., there is a marked
hereditary predisposition to chorea — i.e., "an hereditary
transmission of a special susceptibility to irritation — an
impressionability of the nervous system" — generally asso-
ciated with constitutional debility. Thus, as quoted by Von

137

Ziemssen : — Dr. Huntington, of Long Island, with his
father and grandfather (also physicians) says he has observed
entire families of choreic persons, in which the disease was
propagated until once a generation had been overleapt, when
the hereditary disposition in that family ceased. In these
cases the chorea began between the twentieth and fortieth
year of life ; attacked men and women alike, and usually
led to mental disease, often associated with suicidal tenden-
cies, and finally to death. That chorea may be congenital —
i.e., transmitted hereditarily, admits of no doubt, although
the occasions of such actual transmission may be regarded as
comparatively rare. Fox has recorded a case in which the
child, a male, was born six weeks before the period, and
from the first hour of his life he suffered from violent choreic
movements, which gradually developed into epilepsy in his
third year ; after which he had no further attacks, but his
speaking and walking were defective up to this thirteenth
year. Richter also mentions chorea as occurring congenitally
in the case of two girls whose mothers had been frightened
when far advanced in pregnancy. From their birth the
children suffered with chronic spasms, which ceased during
sleep, and eventually disappeared almost entirely.

That chorea is often mimetically contagious, is also a well-
established fact : thus Leube saw two girls, of the ages of
sixteen and seventeen, hysterically predisposed, who acquired
chorea in consequence of intercourse with another girl, aged
twelve, who had the disease. Bricheteau also mentions the
following interesting case : — A girl was admitted into a ward
in the Hopital Necker where there were girls who were
hysterical, and who had formerly been the subjects of chorea,
and within six days eight other patients in the same ward
where taken with chorea. The further spread of the disease

138

was arrested by isolating the chorea patients. The intensity
of the symptoms varied greatly ; some of the attacks lasted
for months. In connection with such contagious or imitative
cases, the especial point to remember is that a distinct pre-
disposition seems to be necessary to propagate the disease by
imitation : otherwise the number of instances would be
much greater than it is.1

In this connection I may now briefly refer to alcoholism ;
the pernicious effects of alcoholic excesses on the nervous
system being well known, and these are, according to all
competent observers, markedly hereditary in many cases.
In cases of inherited predisposition to chronic habitual
drinking, it is not absolutely necessary that the parents or
ancestors should have been drunkards, but that the family
is characterised by that form of unstable nervous organisa-
tion which I have already alluded to as a neuropathic pre-
disposition, and that the neurotic taint which manifests
itself in other members in such affections as hysteria,
epilepsy, and insanity, will be manifested in these cases by an
intense, if not insuperable, craving for alcohol. At the
same time it should be borne in mind that owing to the
tendency which acquired predispositions have to reproduce
themselves in the offspring, drunken parents may actually
transmit this predisposition to their children, or if not, then
such a state of disordered cerebral nutrition as may express
itself in epilepsy, insanity, idiocy, hysteria, weakened will-
power, or mental instability. Here again we see how
the differentiation of individuals is maintained by patho-
logical processes ; for, given a drunken parent or parents,
their children will assuredly inherit such a neuropathic dis-
position, as in the case of one of them may manifest itself
1 Von Ziemssen.

139

in idiocy, in .another as epilepsy or hysteria, in another in
weakness of will, and in yet another or others in uncontrol-
lable alcoholic craving; some may escape in their own
persons, but only to hand down the heritage of their
parents' shame to others and succeeding generations. Dr.
Richardson has well said : — "The solemnest fact of all
bearing upon the physical deteriorations, and upon the mental
aberrations produced by alcohol, is that the mischief inflicted
by it on man through his own act and deed cannot fail to be
transmitted to those who descend from him, and who are
thus irresponsibly afflicted. Amongst the many inscrutable
designs of nature, none is more manifest than this, that
physical vice, like physical feature and physical virtue,
descends in line. But not one of the transmitted wrongs,
physical or mental, is more certainly passed on to those
yet unborn than the wrongs which are inflicted by alcohol.
Many specific diseases engendered by it in the parent are
too often stamped in the child ; while the propensity to its
use descends also, making the evil interest compound in its
terrible totality." It is unnecessary for me to dilate upon
the many acute and chronic diseases caused directly and
indirectly by alcohol ; but the point on which I would
especially insist is that the protean pernicious effects of
alcohol taken in excess do not, unfortunately, end with the
miserable life of the poor drunkard, but are passed on to
his irresponsible children as a legacy from violated nature —
an indelible brand, an inherited curse — which may express
itself in a distinct neuropathic predisposition capable of
developing insanity, hysteria, epilepsy, impaired volition
or mental instability, and of reproducing the primary vice
in which it has originated. Of the real nature of this pre-
disposition we know nothing, beyond the probability that the

140

nervous centres are somehow implicated in its production,
but we must for the present be content to accept facts as we
find them, and trust that further researches may be able to
throw light upon a subject which is now obscure and
mysterious.

Having now considered the hereditary element in insanity,
hysteria and its allies, epilepsy, chorea, and alcoholism, I
might readily refer also in detail to neuralgia, cephalalgia,
migraine, tubercular meningitis, sanguineous apoplexy, loco-
motor ataxy, progressive muscular atrophy (Cruveilhier's
paralysis), pseudo-hypertrophic muscular paralysis (Du-
chenne's paralysis), sclerosis, and other nervous diseases
which are alike subject to heredity, but I think I have adduced
sufficient evidence to support the principle for which I am
contending — viz., that whether the nervous system contains
the fons et origo of heredity or not, its diseases are markedly
hereditary ; furthermore that the pathological differentiation
of individuals is manifested to an extraordinary degree by
the transmission of nervous diseases, for, given a neuropathic
predisposition in the parents, it is found capable of develo-
ping a tendency in the offspring not only to itself, but also
to hysteria, epilepsy, chorea, insanity, neuralgia, and in fact
to ring the changes on every known variety of nervous dis-
order or disease. Thus we see in every family, the members
of which have inherited a neuropathic predisposition, that it
may not only develop into various forms of nervous disease,
but that each member has inherited something which the
others have not, whilst some may only act as mediums for
transmitting the predisposition to a future generation, and
at the same time they themselves may show no evidence
of its possession. The differentiation of individuals is
absolutely necessitated physiologically and psychologically

by the interaction of heredity with the law of variability, and
so it must be pathologically for the reason I have elsewhere
stated— viz., all morbid action is but a modification or per-
version of some natural or normal action or function ; and
all the physical results constituting morbid structural altera-
tions are mere perversions or modifications of natural or
normal textures, or, at most, analogous textures fabricated
from the same materials by like processes. Every living
individual, therefore, differing as he does from every other
physiologically and psychologically, must also differ from
every other in his pathological tendencies ; and I believe
that ignorance of this fact is the most fruitful source of false
views both in pathology and in practice. As too much stress
cannot be put upon my argument in this direction, I once
more briefly summarise it here. By the law of heredity, all
living beings tend to reproduce themselves in their offspring
physically, mentally, and morbifically ; but owing to the law
of variability which interacts with that of heredity in the case
of every individual, the likeness is never perfect — the ideal
law of heredity that like produces like is never attainable.
We see this even in the case of twins, whose resemblance to
each other, however striking, is still far from perfect.
However much a child may resemble its parents — or one
child another — essential differences will be found externally
and internally, physically and mentally, and with regard to
their pathological tendencies. As in health so also in disease :
Nature preserves the type by varying the individual ; and as
in health so also in disease, the individuality of every living
man is necessitated and maintained by the law of variability.
The phenomena of variability in health are seen in the
physical and mental differentiation of every individual from
every other, however closely allied ; the phenomena of

142

variability in disease are seen in the differences of individual
constitutions, as to their mode of manifesting the effect of
the same morbific cause, and their relative power to sustain
it, and in the metamorphoses or transformation in trans-
mission, to which I have recently alluded. The great prin-
ciple for which I am contending is the due recognition of
individuality in every case presented to us, remembering
always that physical and mental differentiation necessitates
the differentiation of pathological processes ; and that, co-
operating with the great law of heredity which tends to
produce like from like, is the equally potent, if subservient,
law of variability, which necessitates our differentiation from
each other physiologically, psychologically, and pathologi-
cally, and by means of which our individuality is developed
and maintained.

Diseases of the Respiratory Organs. — In proceeding to con-
sider the hereditary element in the diseases of the respiratory
organs, I shall not content myself by merely stating that
certain of these diseases are distinctly hereditary, but
taking a broader view of them all, I contend that, for
reasons insisted upon over and over again in the foregoing
pages, there is a predisposition of tissue inherited by those
who suffer from any of them, as, indeed, there is, and
must be, in all morbid processes which are not distinctly
acquired. As I have already stated the nature of these
predispositions is unknown to us, but of the following fact
there can be no doubt — viz., that physiologically, psycho-
logically, and pathologically, also, the textural and func-
tional peculiarities of ancestors and parents are handed
down to their descendants by heredity in varying pro-
portions, modifiable by variability and the influence of
external circumstances. The law of heredity is inexorable,

143

affecting body and mind in health and disease, so that
every record of disease in a parent's life-history is stamped
indelibly on the tissues of his child. Let me not, however,
be misunderstood ; I do not mean that the diseases of the
parents are handed down in every case as entities to their
children, but that the textural or dynamical peculiarities of
parents, whether inherited or acquired, will undoubtedly
be reproduced, in varying proportions, and subject to
certain modifications, in their children, as, at least, predis-
positions to the same. This is very mysterious ; and
although we cannot understand or explain the processes by
which such effects are caused, we must, as the result of
observation and experience, accept the fact that, as surely
as a child resembles his parent or parents in his or their
external configuration, so assuredly does the resemblance
extend to his internal textures and organs, and even to a
predisposition to the same morbid processes from which
they may have suffered, and which he has inherited from
them.

Pulmonary Phthisis. — Of the diseases of the respiratory
organs none, perhaps, is more dire in its effects, or more
unquestionably hereditary, than pulmonary phthisis or
consumption, which has been known to exist contem-
poraneously with the sources of our historical information,
and to which, according to Hirsch, probably two-sevenths
of all deaths are now due. Without entering into a dis-
cussion of the various pathological theories which have
been broached from time to time as to the real nature of
tubercle, I shall content myself by observing that there is
a correlation, however imperfectly understood, between the
scrofulous and tubercular diatheses, and that while both
are markedly hereditary, the tubercular diathesis is met

144

with only in the scrofulous. " How this inherited diathesis,"
says Ruehle,1 "is produced, or what is its real nature, are
questions beyond our present knowledge; but if the
external form of the body, and mental qualities, can be
transmitted in families through generations, why should
this not be the case also with the conditions which produce
a disposition to certain diseases ? If in the former case
we do not demand that the comparison be made only
between children and their parents, but include also the
grandchildren and nephews, why should we not observe
the same rule in regard to the inheritability of disease ?
Why do we narrow the question to asking whether the
father or the mother is known to have the same disease at
the time of conception ? Is not a disease often present
before it can be recognised ? May there not be a dis-
position sufficient to be transmitted, although it does not
manifest itself as a recognisable disease until afterwards ? "
In answer to such questions as these, I unhesitatingly reply
to each of them in the affirmative. For, in the first place,
as heredity is a law of our being, and as the material,,
functional, and dynamical peculiarities of ancestors and
parents are transmitted by them to their descendants, it
assuredly follows that the conditions which produce a pre-
disposition to any morbid process are also transmissible.
We are too liable to narrow down the question of hereditary
descent as if affecting only the qualities inherited by a.
child from his parents, whereas it is a matter affecting
the evolution of the race. Every living individual has
been dependent upon some other or others as far back as
the history of man is recorded by the hand of time ; for
has not every unit of the human family originally sprung

1 Ziemssen, vol. v.

145

from one source ? and if we could each trace our pedigrees
back into the ages when man first made his appearance
upon earth, we should find them all converging in him the
primal and earliest father of our race — whose brow first
shone with the divineness of humanity. If heredity is a
law of our being, it has been so since man first appeared
on earth ; let us see how this affects the question. Let us
take the case of any living individual : he must have had a
father and mother ; these also must have had fathers and
mothers ; and these also ; and so on back through the
ages to the earliest parents of the human family. We may
regard health and disease as coeval with human life ;
therefore the pedigree of disease is not to be regarded as
of recent origin, or its sources traceable to recent influences,
but rather to be found in the records of the earliest history
of man, wherein we may read the "record of its long
descent." Throughout the ages, and amid the many altered
conditions of the earth, man has been much the same as
he now is, as far as his subjection to the laws of heredity and
variability ; the same in barbarism as in civilisation ; the
same with regard to his health and his diseases ; it therefore
follows that whilst the influences of heredity are strongest
upon him, the more closely he is subjected to the influences
of his more immediate ancestors, all the past may be said to
slumber in him. We should not therefore regard hereditary
descent as affecting only the transmission of the parents'
peculiarities to their children, but also the transmission of
qualities derivable from earlier, and even remote, ancestors.
How necessary this is we can infer from the frequency with
which latent or dormant peculiarities — traceable to some
remote or collateral member of a family — develop themselves
unexpectedly in some of his descendants ; and thus it is that

146

every patient who comes before us is made up of such a
mingling of temperaments, idiosyncrasies, and diatheses, as
can only be appreciated, and that imperfectly, by even the
keenest diagnosis ; and of inherited peculiarities of tissue,
and function, and dynamism, which may be active or latent ;
of potentialities or deficiencies which morbid processes can
alone reveal.

But to return. Statistics are, and can only be, unreliable
and valueless in regard to the percentage of inherited cases
of phthisis, and we can only accept the concurrent testimony
of every age, which is so strong that it cannot be doubted
or rejected. Whole families have been exterminated by
phthisis, and according to Horlin, as stated by Hirsch, in the
island of Marstrand, where only one person had died of
consumption during seven years, there were five consump-
tives then living there, four of them sisters, whose mother
had died from this disease. The inherited predisposition to
consumption may reveal itself in different ways — sometimes
in constitutional delicacy, sometimes in special local affections
of the thorax or its organs — and these may or may not be
observed at birth or during childhood, but are generally
noticed at a later period, as, for example, at the time of
puberty, when growth and development are more rapid.
However we may subdivide the inheritability of phthisis we
cannot but regard it as a factor of prime importance in the
etiology of the disease. Although this predisposition is
commoner perhaps among women than men, and its trans-
mission more common through the mother than the father,
yet where one parent only is affected fathers transmit more
readily to sons, and mothers to daughters, than the converse.
Dr. Pollock lays stress on the influence of hereditary pre-
disposition in the acute forms of phthisis, and states that out

147

of 179 cases only 34 could positively declare absence of
family taint. Dr. Theodore Williams says the principal
effect of the predisposition is to be seen not in any peculiarity
of the symptoms, but by the influence it exercises over the
age of attack, which is much earlier in those predisposed
than in others.

Regarding phthisis as a disease essentially belonging to
those which are dependent upon an inherited predisposition,
and as the concurrence of several conditions is usually
necessary for the development of chronic diseases, we must
differentiate between those conditions which are inherited
and those which may be acquired. Of the former we must
recognise a congenital defectiveness of resisting power, which
although not synonymous with weakness, may be associated
with it. This is generally manifested in the children of
weakly parents, or of closely-related inter-marriages, or when
there is a marked dissimilarity in the respective ages of the
father or mother, or when repeated pregnancies have followed
each other in rapid succession. " Usually in such persons
one or several parts of the body are again and again the seat
of disease, and form the locus minoris resistentia. If this be
situated in the respiratory organs, frequent and long-con-
tinued catarrhs of the nose, larynx, and air-passages occur,
and perhaps give rise ultimately to pulmonary diseases which
develop into phthisis."1 This condition is essentially trans-
missible, as is also scrofula, another of those conditions
which usually concur in the production of chronic diseases.

There is a point of some importance to which I should

have referred before, and which I may now be permitted to

allude to, especially as it exercises a modifying effect upon

the influence of heredity generally, and to a great extent

1 Ruehle, Opus cit.

148

affects the inheritance of disease — viz., that which has been
denominated "the tendency to reversion from all variations
of specific characters ;" for, as the preservation of the specific
characters of the species essentially concerns the law of
heredity, the determination of individual characters is mani-
fested most in the law of variation : and thus, the inheritance
of a disease-tendency, however probable, is not invariable,
as disease-tendencies, like parental characters of mind and
body, are either held in check or actually neutralised by one
of the parents of the child being healthy, so that the con-
stitutional disease of the other may be, in a manner diluted.
"Phthisis," says Dr. Maudsley, " is a notorious instance,
passing so directly from parent to child, as to entail the ex-
tinction of a family when it is not neutralised by favourable
inter-breeding. For such neutralisation, not of phthisis only,
but of other disease-tendencies, may undoubtedly be effected,
although we have not at present any knowledge of the laws
by which the good result is brought about ; the fact, how-
ever, is certain, and profoundly significant. The union of
two individuals, one of whom has a marked disease-tendency
of a particular kind, produces an organic constitution in
which it is held in neutralisation or check, never showing
itself in their children. It has become a disease-immunity
for that generation. Did we know the exact nature of the
neutralising process it would no doubt be possible, by suit-
able arrangements for subsequent breeding, to get rid entirely
of the morbid tendency and to obtain a perfectly sound stodk.
Unfortunately we do not, and so are liable to find the neu-
tralisation temporary, since it not unfrequently happens that
the union of the offspring which is apparently free from the
disease-tendency, because it is held in check, with a person
is also apparently free from it, produces an organic

149

nature in which it shows itself distinctly. It is somehow
made a disease-aptitude again." Sir James Paget says :
" Through such dilutions and such tendencies towards re-
covery of health in embryo-life, and in a less degree after
birth, we may believe that many of the lesser constitutional
diseases are derived ; but of the rate of diminution in trans-
mission, and of the possible changes of form associated with
changes of intensity or quantity of disease, we know very
little, if anything. And very little we know of the results
of the transmission of more than one constitutional disease
to the same offspring. We can often see plainly that the
forms in which different persons display a constitutional
disease appear very different from those seen in their parents.
Thus, in a family of which one or both parents had typical
gout, or tuberculosis, or scrofula, there may appear any num-
ber of the lesser forms of these diseases, or of the forms
deviating furthest from the type. And yet a certain general
similarity may appear in all the local manifestations of each
constitutional disease thus variously transmitted. They may
be unlike in structural appearance while affecting different
structures, and yet they may be like in their time-work, or in
the production of some characteristic morbid product, or in
the influence which medicines or diets exercise on them.
These things may prove the same constitutional origin in
apparently very different local diseases." This long digres-
sion may, I trust, be excused, as I had omitted to refer par-
ticularly to those neutralisations or checks to inheritance
which frequently result from favourable inter-marriages ;
but it will be seen that these neutralisations or checks
— however they may be perpetuated in theory — are in
the majority of instances nothing more than examples of
atavism, and that the original disease-tendency is transmitted

to a generation by heredity, subject of course to the law of
variability so far as individual characteristics are concerned.
To return, however, to the further consideration of the
diseases of the respiratory system as subject to the influence
of heredity, I may regard pulmonary phthisis as a typical
constitutional disease occurring in persons of the scrofulous
diathesis. When considering the diatheses I was careful to
point out that their development, in the great majority of
cases, required many generations in which to accomplish it,
for they are in reality peculiarities of health amounting to
morbid tendencies which have been accumulated and inten-
sified in their long descent so that we can now recognise
them as types of constitutions with which are generally asso-
ciated certain well-known forms of disease. Of these dia-
theses which were termed universal, because they are not
only as old as the race, but because every individual is more
or less subject to their influence, are the scrofulous and the
catarrhal ; there is surely, therefore, no occasion to prove
transmissibility ! These may co-exist or be blent in varying
proportions in different individuals, and it may be stated as
an axiom that the more the scrofulous diathesis preponder-
ates, the greater the danger of catarrhal attacks in an
individual. Mr. Hutchinson has well defined scrofula as a
permanent and heritable condition, favouring chronicity in
all inflammatory processes, and directing them towards more
or less specialised ends ; and catarrh, as inflammatory con-
gestion excited, in a reflex manner, through the influence
of cold applied to the surface : therefore, whatever is the
result of " catching cold " is catarrhal. He says : " The
susceptibilities of the nervous system, however, in this
direction differ, as we all know well, very greatly in different
individuals. These differences are hereditary, and may

easily become the possessions of families or of race. Not
only do individuals differ in the degree of reflex susceptibility,
but they also vary much as to the special tissues or organs
which are most prone to suffer under it. Thus, some catch
cold almost solely in the mucous membrane of the nasal pass-
ages and pharynx; in others, the tonsils, throat, and larynx are
much more prone to suffer ; in others, the bronchial mucous
membrane, etc." To these two diatheses, therefore, I trace
the heredity of the majority of the diseases of the respira-
tory system, for it will be found that by far the greater num-
ber of them are included under the heads of scrofulous or
other well-recognised constitutional and heritable conditions,
and under that of the universally-developed catarrhal dia-
thesis. Thus under the head of scrofulous diathesis may be
included chronic tubercular phthisis, acute miliary tuber-
culosis, pleural tuberculosis, and, perhaps, gangrene of the
lungs ; whilst under that of the catarrhal diathesis we may
range croupous and catarrhal pneumonia, croupous or
fibrinous bronchitis, bronchitis, croup, coryza, rhinitis blen-
norrhoica, acute and chronic laryngitis, catarrhal tracheitis,
bronchial catarrh, pleuritis, tonsillitis, etc. In this list I do
not include pulmonary emphysema, and bronchial asthma,
which are, however, well-known to be hereditary. Various
other so-called diseases of the respiratory organs might be
mentioned, as pneumo-thorax, hydro-thorax, haemoptysis,
atelectasis (often congenital), oedema, etc., but as these are
for the most part merely symptomatic of other diseases, I
shall not now further allude to them.

What I am contending for is not that all the diseases of
the respiratory system are hereditary or heritable as such,
but that in the case of each of them there is a predisposi-
tion which is inherited by every individual affected by them ;

and that this predisposition of tissue, cell or membrane,
unless neutralised or held in check by marriage into a
different stock, will inevitably reveal itself, and if not in one
generation, it will assuredly in the next; for as Dr. Maudsley
says : " A disease-tendency, which is latent or dormant at
one period of life, or throughout the whole life of the
individual, may undergo actual development at a particular
physiological epoch, or on occasion of a great bodily crisis
from some other cause ; and a tendency which is latent or
dormant in one generation may show itself in the next gener-
ation." Nothing in nature is lost, and whether for weal or
woe to the individual, her laws are inexorable, and must be
obeyed. Heredity is the law as affecting the characters of
the species ; whilst the individuals are subject also to that of
variability, thus necessitating the differentiation of indi-
viduals. On the whole, however, we inherit from our
ancestors and parents not only our bodies and our minds,
but a predisposition to their diseases ; and of the latter none
more surely than those of the respiratory system. For
of the diseases of the respiratory organs, nearly all have their
source and origin in the scrofulous and catarrhal diatheses,
and these in themselves the result of inheritance in past
ages have been handed down to us, modified or intensified
as the case may be, by our fathers.

Diseases of the Kidneys, etc. — That a predisposition to
diseases of the kidneys, bladder, and generative organs, is
hereditarily transmitted, and characterises certain families
for generations, is a fact which cannot be denied ; and if
my arguments as to the influence of heredity in the diseases
of the circulatory, nervous, and respiratory systems are of
any avail, we shall have no difficulty in understanding why
this is and must be so. For the human body being subject

to the law of heredity in its every organ and tissue, it
assuredly follows that what is true physiologically and
psychologically, must, as a natural sequence, be true also
pathologically. We are prone to talk of the constitution
of an individual. What do we mean by the term, and what
does it involve ? A sound constitution has been defined as
the harmonious development and maintenance of the
tissues and organs of which the body is made up. Whence
does it originate? From the union of a healthy sperm
and germ cell in the maternal womb. To this same union
I have already traced the source of heredity : so that every
constitution has its foundation laid, and its deficiencies
and potentialities developed and maintained in accordance
with the law of heredity, to which they are alike subject
from the time a germinal vesicle is produced by the fusion
of the germ with the sperm cell. Irrespective of the
definite inherited forms of disease which contribute to consti-
tutional unsoundness, the latter condition may also be the
result of defective or deficient vitality, which may be general
or local. When general, this deficient vitality is frequently
observed in " the children of parents one or both of whom
are in advanced life, or whose vitality on one side or the
other has been reduced by excesses, such as alcoholic or
venereal. Exhausted vitality from prolonged disease, e.g.,
phthisis or tertiary syphilis, affecting either parent, may
determine the death of the offspring at an early period
from mere failure of nutrition, or may cause it to succumb
to acute disease not necessarily associated with any inherited
tendency of a special kind." Deficient vitality may also be
local, i.e., affecting only certain tissues and organs, or
involving certain systems, as the nervous, the respiratory,
the vascular, generative, or digestive ; and amongst those

154

diseases which are the most assuredly and markedly
hereditary, none are more so than those of a degenerative
form, including structural heart diseases, atheromatous
vessels, emphysema, certain diseases of kidney, etc. All
these partake of the nature of premature senility of organ
or tissue, consequent upon some inherent deficiency in
their vitality. " Although the constitution of an individual
begins with his life, it is nevertheless the resultant of the
constitutional peculiarities of many antecedents. This being
so, tendencies to disease may date far back in the pedigree,
to be called forth from time to time by favouring circum-
stances." What we have practically to remember is, that in
addition to such definite inherited forms of disease as
congenital syphilis, gout, scrofula, tuberculosis, cancer,
asthma, and several neuroses, the relative soundness or
unsoundness of individual constitutions is also dependent
upon a local or general defectiveness of vitality, which is
hereditary, and which will tend to develop disease in the
impaired organ or tissue. Constitutions are liable to be
rendered unsound, not only by definite inherited forms of
disease and defective vitality, but by the wear and tear of life
in its environment. Here again we have the constitutional
vigour so impaired, subsequently to birth, by pernicious
surroundings, that constitutional diseases are thus engendered
and passed down as a legacy to be inherited in future
generations, in the form of scrofula, rickets, phthisis, etc.1

We thus see that there is no organ or tissue of the human
body which is not subject to heredity in disease as in
health : the fact being that, in one as in the other, like
begets a predisposition to like, capable of being modified
by variability, or even neutralised by marriage into a new
1 Dr. Douglas Powell.

155

stock, for a generation, but never lost A predisposition to
degenerative diseases of the kidney is therefore as much
a fact as that scrofula or phthisis are the results of the
development of a pre-existing disposition in the organs or
tissues affected by them. The three degenerative diseases
of the kidney known under the generic name of Bright's
disease will afford an example. The first, or inflammatory
form, may be acute or chronic, and usually affects the
tubules; the second, or waxy, lardaceous, amyloid or
albuminoid is degenerative, and originates usually in the
vessels ; whilst the third, the gouty or cirrhotic form, is
also degenerative, and originates in the fibrous stroma.
What has heredity to do with these conditions ? Let us seek
our reply in the etiological sources of each of these
affections. The inflammatory affection is said to be caused
by exposure to cold, and by scarlatinal and other blood-
poisons : the latter I shall consider presently, when I come
to deal with heredity as affecting the acute infectious
diseases. With regard to exposure to cold, we have already
seen that the catarrhal diathesis is universal, but may be,
and is, differently distributed in different individuals. Let
us suppose, for example, that a parent has in early life
suffered from this inflammatory affection of the kidneys,
however caused : however competent to discharge their
functions afterwards, the kidneys during his life will bear
the brand of what they have suffered — they will be somehow
different from what they were originally. This parent has
a child or children who have, in common with humanity,
inherited the catarrhal diathesis, subject in his or their
cases to the combined catarrhal predisposition of both
father and mother. From what we have already seen of
the action of heredity, is it too much to assume that one of

156

the father's children will inherit a predisposition to the
pathological taint in his father's kidneys, and on exposure
to a similar cause will almost inevitably suffer from a
similar affection ? I trow not ; but, unfortunately, I have
no cases at my disposal to bear out my argument. At any
rate, it is easy enough to adduce cases of like heredity in
reference to other organs and tissues, and if so in these,
why should the kidneys be excepted ? I firmly believe that
as every vestige of the human body is subject to heredity
physiologically and psychologically, so it must be, and is,
with regard to its pathology : for disease is but impaired
function or degenerative change ; and if, in health, every
cell, membrane, muscle, bone, and viscus — every element
of man in his dynamism — is subject to the law of heredity,
by a parity of reasoning, I cannot see why, if certain
morbid conditions are universally recognised as hereditary,
a predisposition to every morbid condition may not be
traced to the same influence.

The waxy or amyloid disease of the kidneys is said to be
caused by phthisis, syphilis, caries, profuse suppuration,
and other exhausting conditions, and is often associated
with waxy degeneration of other organs, especially the
liver, spleen, and intestinal canal : in fact, it might be
defined generally as a constitutional condition dependent
upon the scrofulous diathesis. As in the foregoing, and
for similar reasons, this condition is capable of being
transmitted hereditarily, at least, so far as a predisposition
to its development is concerned. The gouty or cirrhotic
form of Bright's disease depends for its causation upon
alcoholic intemperance, the poisons of gout and lead, and
others conditions which are unknown. In the course of its
development, hypertrophy of the heart, with sclerosis and

•degeneration of the vessels are frequently associated with it,
insomuch that Sir William Gull and Dr. Sutton regard
the affection as only symptomatic of a constitutional con-
dition characterised by hypertrophy of the walls of the
small arteries, due to a fibroid growth in the external coat
of the vessels. Dr. George Johnson, on the other hand,
regards the hypertrophy as " a consequence of the obstruc-
tion which impure blood invariably meets with in the
•capillaries." Whichever view may be correct, I have
certainly seen cases in which the cirrhotic form of kidney
disease was associated with cirrhosis of the liver, sclerosis
of the blood-vessels, mitral stenosis, and curiously enough,
with sclerosis of the posterior 'columns of spinal cord.
There is, at least, much in favour of the belief that the so-
called "gouty kidney" co-exists with a constitutional con-
dition, however imperfectly understood, and that like all
other constitutional conditions, it is capable of being trans-
mitted, as a predisposition, hereditarily. I have chosen the
three forms of Bright's disease as illustrative of my argument
because in themselves they constitute the most important of
the diseases of the kidney ; but I might readily have in-
cluded syphilitic, malignant, and tubercular disease, suppur-
ative inflammation, * acute and chronic atrophy, cystic,
hydatid, and fatty disease, pyelitis, etc. Those to which I
have referred are, however, I trust, sufficient to show that as
in every other organ and tissue of the human body, the
kidneys are similarly predisposed to disease, and that this
predisposition is hereditarily transmissible.

Renal and vesical calculus — similar morbid conditions —
are undoubtedly hereditary. I could adduce many striking
instances of this fact, but the following will suffice : — The
first case is mentioned by F. Hoffman. The Lady of the

Prince Moritz of Zeitz was afflicted with nephritis ; she was
delivered of a daughter, who, from the moment of her birth,
suffered very great pains, especially when passing water.
The child lived only three weeks. At the post-mortem
examination there was found in the bladder a stone as large
as the stone of a peach (instar mail Persici). Gaubius, as
alluded to by Steinau, assisted at a lithotomy performed on
a boy of ten years of age, whose father had, twenty-five years
before, undergone the same operation. The father, upon
seeing the stone taken from his son, assured them that it was
quite like that taken from himself. Gaubius compared
them ; and found they were indeed like each other in every
respect, except in size, the father's being somewhat larger
than that of his son. There is also the well-known case of
the Perigordian philosopher, dear, quaint old Montaigne, who
suffered severely from stone in the bladder, which he had
inherited from his father. Stahl also assures us that he
never saw a person suffer from lithiasis, whose father or
some other near relation had not been afflicted with this same
complaint, or with gout.1

The different maladies peculiar to women, according to
the opinion of the most skilful observers, frequently occur
hereditarily, or are transmitted as a predisposition to the
same. Nothing is of more frequent occurrence, says
Stahl, than to see all the different irregularities of the
menses, pregnancy, puerperium, the milk, etc., that had
taken place in the mother, appearing also in the daughter ;
and every observant physician must have frequently noticed
this fact. The relative susceptibility of individuals to the
syphilitic and gonorrhceal virus — to stricture, catarrhus
vesicse, enlarged prostate — all of which involve a hereditary
1 Dr. Steinau.

159

element, might be here noticed, but I shall allude to some
of these affections hereafter. I therefore, maintain, that
in all diseases of the kidney and genito-urinary tract there
is a pre-exisiting heritable disposition of tissue and organ,
whether of late or early descent, and that this view is well
supported by facts in every-day practice, if they are only
recognised and appreciated aright.

Diseases of the Chylo-poietic System. — The mere enumera-
tion of these diseases would monopolise almost all the
space at my disposal for their consideration. I shall,
therefore, content myself with some brief general remarks
as to how they are affected by heredity. If there is any
truth in my previous statements regarding the diseases
already considered, and if my arguments have anything to
recommend them, it follows, by analogy — if I have estab-
lished as a fact that pathological processes are subject to
heredity because the physiological and psychological nature
of man is undoubtedly inherited, although subject to indi-
vidual modifications — that what is true of one system must
be true of all, and that as every tissue and organ in the
human body bears the brand of heredity in the discharge
of their every function in health, so must they also in
disease, which I regard as functional derangement or
degenerative change in tissues or organs which have been
inherited. Again I must guard myself from being mis-
understood. I do not mean that the diseases of ancestors
or parents must inevitably be transmitted to their children
(although such cases occur, perhaps, more frequently than
we wot of) ; but what I contend for is that the physiological
and psychological natures of ancestors and parents being
handed down to their children, with certain individual
modifications, it must follow that the brands of disease

i6o

upon, or the taints of disease within their tissues or organs,
must be likewise transmitted as predispositions to the same.
When considering the physiological and psychological
aspects of heredity, in this series of papers, I think I
proved without a doubt that there was no element of man
either in his organism or in his dynamism that was not
subject to the law of heredity ; and if this is so it seems
to me but a natural consequence that with his organic or
dynamical peculiarities he should also transmit a predis-
position to the weakness or deficiency of his tissues or
organs produced by disease in himself, to become re-
developed in his children under circumstances favourable
for such development.

With regard, however, to the diseases of the stomach
and intestines, of the pharynx and oesophagus, of the
peritoneum, of the spleen and pancreas, if heredity and varia-
bility necessitate the fact that these organs differ from each
other not only organically, but functionally in the cases of
different individuals, and that in no two individuals are
they precisely the same either in their organic potentialities
or functional peculiarities, it assuredly follows that they are
differently predisposed to organic and functional derange-
ments and diseases, and it is only fair to assume that here-
dity and variability are also responsible for this fact It is
at least safe to affirm that all the diathetic diseases —
tubercle, scrofula, cancer, syphilis, gout, et hoc genus omne
— are markedly hereditary, and that every organ and tissue
of the chylo-poietic viscera are subject to each and all of
these diseases admits of no doubt. Of other morbid con-
ditions of the chylo-poietic system which are frequently
inherited I may mention helminthiasis, haemorrhoids, dys-
pepsia, hernia, fcetor oris, and dropsy ; to these might be

added many kindred conditions, but those mentioned will
suffice. With regard to helminthiasis it is a fact, as proved
by daily experience, that the children of parents who are
infected by intestinal worms (especially ascaris vermicularis
and ascaris lumbrico'ides] are also attacked with these para-
sites, often at a very tender age, when they cannot have
been caused by any noxious influences ; and sometimes
even from their very birth. Dr. Steinau says he had fre-
quent opportunities in the Hospital for Diseased Children,
in Berlin, to assure himself of the hereditary character of
this complaint. The hereditariness of haemorrhoids is of
too frequent occurrence to render it necessary to enlarge
upon it. Who has not witnessed dyspepsia, in its protean
forms, handed down from parent to child, and been struck
by the frequency a patient will say " My father (or mother)
had a very weak stomach too ? " Hernia has been known
to have been inherited through many generations. Many
competent writers, says Steinau, have cited cases to prove
this ; and Richter saw several children, whose fathers were
ruptured, suffering from the same complaint, having in
each case arisen without any external cause, and quite spon-
taneously. Speaking of dropsy, Rougemont, supported by
the testimony of several credible writers, says that it is
proved by numerous observations that the children of such
parents as have died of dropsy became at a certain age also
dropsical. Many cases have been noticed of dropsical
women being delivered of dropsical children — particularly
one case quoted by Hufeland, and observed by Olivier.
Chronic foetor oris, which does not appear to be produced
by any visible local cause, is also often hereditary.1 To
these might be added abdominal cramp, flatulence, con-
stipation, pyrosis, and many other allied conditions.
1 Steinau.

162

Regarding the diseases of the chylo-poietic system as a
whole there is scarcely one of them to which heredity can-
not be said to have predisposed. Of course the influences
of life and circumstances have to be estimated in every case
as factors in the production or development of disease ; but
I maintain that in almost every case there is a pre-existing
disposition which has been inherited, and which acts as the
source from which morbid processes spring, or as the
foundation on which they are laid. To quote an-illustration
already given, why should several individuals exposed to the
same noxious influence — say a chill — be so differently
affected ? One will have as a consequence an attack of
influenza or bronchial catarrh, another sore-throat, another
rheumatism, another bronchitis or pneumonia, another lum-
bago, and so on. Why are some individuals so prone to
attacks of erysipelas, biliousness, sick-headache, etc. ?
Because they differ from each other as individuals in power
of resistance ; because of pathological habit ; but principally
because of constitutional predisposition which in nine cases
out of ten, will be found to rest upon a basis of heredity.
Their fathers or mothers may be found free from any such
affection as the children respectively suffer from ; but this is
not enough to prove their non-hereditary origin. We must
enlarge the cycle of heredity and inquire further back in the
pedigree, and if this inquiry also gives a negative reply we
must remember that hereditary diseases are somehow
mysteriously related to each other, and may in many in-
stances be found vicarious; thus it is possible that the father
may suffer from haemorrhoids, and the son from dropsy ; or
the first from gout and the latter from stone ; but still in
these cases the dropsy as well as the stone must be con-
sidered as hereditary.

i63

Try as we may, there is no such thing as getting rid of
heredity, for it is the inexorable law of our being. No
force in Nature can be lost ; and as whatever we have or
are we owe to heredity, save the action of our environment,
we must bow to the inevitable, and admit that as our
physiological and psychological being is subject to the
action and interaction of this great law within us, so also
we are more or less predisposed to the morbid processes
which assail us during our lives, and that these predisposi-
tions we shall pass down to our children, however ignorant
we may be of the fact, or however we fail to recognise or
appreciate it. As the past slumbers in each one of us, so
do the potentialities of the future — the welfare and
commonhealth of our race !

Hepatic Diseases. — The foregoing arguments as to the
influence of heredity in diseases and disorders of the kidneys
and chylo-poietic viscera, apply with equal force, for obvious
reasons, to diseases and disorders of the liver. I need not
here recapitulate them in any detail. Of the degenerative
diseases of the liver — cancer, cirrhosis, amyloid degeneration,
fatty infiltration, etc., it may be safely said, irrespective of
their proximate causation, that, at least the majority, if not
all of them, are dependent upon constitutional conditions,
and that a predisposition to each of these, either in the
person of the afflicted parent or of his children, is more or
less, but almost invariably, inherited. Let us briefly consider
these diseases of the liver in the above-mentioned order, and
with especial reference as to how they are affected by heredity.
With regard to diseases of the liver in general, Frerichs in
his great work remarks that " the data heretofore established
are not sufficient to secure to heredity a positive influence."
That he was at least mistaken with regard to hepatic cancer,

164

there cannot be the least doubt ; and if in one case, why
not in all ? It is only fair to assume, that at the time this
distinguished and original writer published his magnum opus
(1858), the subject of heredity in relation to disease was
comparatively little understood, and that the mind of the
author had not been especially directed towards its con-
sideration. It has long been generally acknowledged that
the heredity of cancer is well established, and "that which
applies to cancer, in general, self-evidently and as a matter of
experience, equally applies to cancer of individual organs."1
Statistics are not very reliable as a rule, but even these prove
without a doubt that cancer is hereditary. Thus of 1127
cases reported by Paget, Cooke, Sibley, Lebert, Lafond,
Hess, Moore, and others, 192, or 17 per cent, were found to
have been inherited ; and I have already elsewhere recorded
a case in the practice of the late Dr. G. H. Barlow, in which
a lady was the fifth victim of cancer of the liver in two
generations.

In such a case as the last, one cannot fail to be struck
with the hereditariness of cancer ; but it should never be
forgotten that, although diseases and predispositions, being
subjected to the influences of other diseases and predis-
positions, are not unfrequently reproduced hereditarily in a
modified form, yet that the heritable influence always exists
in one form or another. Cirrhosis of the liver offers a case
in point. What are its causes? (i) Spirit drinking, a
predisposition to which is undoubtedly heritable ; and who
can say that a predisposition to its effects corporeally is not
also transmissible ? (2) Syphilis ; can there be any doubt
as to the inheritance of this disease ? (3) Malaria, as we
have seen in the consideration of the malarial diathesis, is
1 Leichtenstern.

potently hereditary. The other known causes of cirrhosis
of the liver are subsidiary, and need not here be considered.
Here then we have an affection, the three main causes of
which are indubitably subject to heredity, and however
diverse in their nature, yet tend to produce a well-known
disease of the liver ! Here we have an example of the
manifold and complex influences of heredity on the human
system in relation with its diseases, and it should always
be remembered that there are many cases in which, although
like cannot be said to produce like, yet the influence of
heredity is potent and effective. When alluding to cirrhosis
of the kidneys, I stated that it was frequently observed as
part of a constitutional condition characterised by fibrotic
changes in vessels and organs ; these observations are,
however, still sub judice, so I shall not insist upon their
accuracy, but I have, at least, shown that the causes of
cirrhosis of the liver are mainly heritable, and if so, I
cannot see why their effects should not be so also. If a
predisposition to allied pathological changes or conditions
is inherited, as it unquestionably is, I fail to recognise the
mode of reasoning which would exclude cirrhosis of the
liver — or at least a predisposition — from the same category.
Amyloid degeneration, whether of kidneys, liver, or other
organ, never appears as a primary affection, but as the result
of a pre-existing general cachexia, induced by various morbid
conditions usually associated with prolonged suppuration,
ulceration of bones and joints, also of soft parts (as in
empyema), or with chronic pulmonary phthisis, constitutional
syphilis, or other chronic constitutional diseases. Like most
other constitutional conditions, the cachexia, however in-
duced, may be transmitted, whether associated with amyloid
degeneration or not; and what is still more to the point,

L

i66

according to Rokitansky and other observers, amyloid
disease, and especially amyloid disease of the liver, has been
known to occur actually as a congenital condition in cases
of hereditary syphilis. There is therefore no reason why a
predisposition to amyloid disease of the liver or other organs
should not be inherited. If not a product of the scrofulous
diathesis, amyloid disease is certainly the resultant of a pre-
existing condition closely allied to it.

I may dismiss the consideration of fatty infiltration, or
fatty degeneration of the liver, in a few words. Both may be
regarded as modifications of the natural fat-forming process ;
in the first case being brought to the liver-cells with the
blood ; in the second, originating in the interior of the liver-
cells themselves, from the albumen belonging to them. The
first partakes of the nature of that general condition which
we term obesity or corpulence, a predisposition or tendency
to which is handed down from one generation to another ;
the second partakes of the nature of metamorphosis — fatty
atrophy of the cells, resulting from the non-restoration of
albumen expended in the preparation of fat. This latter
condition is also hereditary, and may involve other organs
than the liver, as the heart, etc.

Passing now from degenerative diseases to functional
derangements of the liver, I may here briefly allude to chole-
lithiasis or gall-stones, icterus or jaundice, hepatic congestion,
and "biliousness," which are all more or less hereditary.
Fauconneau-Dufresne asserts that gall-stones are frequently
hereditary, basing his assertion on the experience of the bath
physicians at Vichy, who have so many opportunities of
observing every kind of liver disease. Be this as it may, we
cannot say that gall-stones, or a predisposition to them, are
not hereditary, simply because from our inexperience or

i67

ignorance we cannot say whether they are or are not. If
the views enunciated in the foregoing pages 'have anything
to support them, we should have no difficulty in under-
standing why gall-stones should be hereditary, like other
morbid results, and we can only trust that time and experience
will ultimately clear the way from every doubt, either one
way or the other. Icterus or jaundice is also hereditary;
thus Kerkring mentions an example of a woman afflicted
with jaundice, being delivered in the eighth month of her
pregnancy of a still-born child, whose very bones had a
yellow colour. This case seems to support the views of such
pathologists as Hartmann, Conradi, and others, who believe
that in many cases, instead of a mere predisposition com-^
municated by the parents to their children, the disease itself
is inherited ; and they appeal to experience, by which it is
proved, as they allege, that many children are born with
diseases under which their parents suffered. We must
acknowledge that deformities generally, and especially
anomalies in the external parts, as varus, sex-digitism, also
diseases of the eye, especially cataract, if inherited are
brought into the world with the children ; but, on the other
hand, in the majority of so-called internal diseases, a predis-
position only is more frequently inherited. Probably the true
explanation may be found in the following circumstances —
viz., that with respect to the majority of internal diseases, it
often depends upon the more or less high stage to which the
disease has arisen in the parents, whether they communicate
to their children merely a predisposition, or the disease
itself. How it happens, however, that sometimes the
predisposition only, and sometimes the disease itself, is
communicated, must, like many other questions, for the
present remain unanswered. In addition to the case of

1 68

hereditary jaundice observed by Kerkring, many other
observers have seen interesting cases of women, afflicted
during their pregnancy with icterus, having been delivered
of jaundiced children. No less scarce are the cases where
all the members of a family have been attacked by jaundice
at the same age; and an especially remarkable one is
described by Boerhaave.1

That there is an especial predisposition on the part of the
patient to the hepatic congestion induced partially by
dietetic irregularities, peculiar to middle life, cannot be
doubted, and if we consider how different individuals are
differently affected by free indulgence in innutritious diet and
irritative articles of food, whilst at the same time leading a
sedentary and inactive life, the reason is not far to seek, for
as individuals differ from each other in every respect,
physiologically, psychologically, and pathologically, so must
each individual differ from every other in his inherited
tendencies. How else can we explain the reason why
amongst a set of freely-living indolent men one will suffer,
in consequence of his mode of life, from hepatic congestion,
another from obstruction, another from constipation, another
from haemorrhoids, etc., while others remain free from any
such disorders ? Apparently the mode of life has much to
do with the production of such conditions, but primarily,
the inherited predisposition influencing every organ and
tissue of different individuals in various ways and degrees,
alike in health and disease, constitutes the real reason.
Virchow has already demonstrated very considerable in-
dividual differences in the conditions of the arterial walls :
why then should the occurrence or non-occurrence of the
above-mentioned conditions under precisely similar circum-
t Steinau.

169

stances not be accounted for by individual differences in
the condition of the walls of the vessels belonging to the
portal system ; nay, more, to individual differences in the
development, nutrition, and innervation of the muscular
tissue of the intestines ? These relative individual differences
of bone, tissue, cell, organ, membrane, and vessels, which
are admitted by all competent authorities, really form the
foundation of all sound views in pathology, and the more
they are recognised and appreciated, the more will the art
of medicine acquire scientific exactitude and increased
usefulness to humanity. In the words of Sir James Paget,
" Better treatment will follow better diagnosis, and better
diagnosis will certainly follow a more exact pathology."
Professor Thierfelder, of Rostock, says : " The predisposition
to habitual hepatic congestion is often inherited, and may
then appear in the same families for many generations.
It must obviously be admitted that there may exist a
similar predisposition towards a menstrual hyperaemia of the
liver. A somewhat analogous condition is suggested also
in that form of hyperaemia due to obstruction. In certain
affections, for instance, it is not always the liver, but
frequently the kidneys or the mucous membrane of the
digestive apparatus, that constitute the organ in which the
results of over-distension of the entire venous system first
of all and most distinctly appear ; and with reference,
moreover, to the degree of the alterations in the liver, the
separate cases present varieties which are by no means
invariably proportionate to the extent of the obstructions to
the circulation, in consequence of which, as is stated by
Botkin, the susceptibility of the liver to the effects of an
increased venous pressure cannot be the same in all
individuals."

170

Biliousness, or bilious attacks — however vague the terms,
and however incorrectly applied — are very frequently merely
attacks of acute dyspepsia or migraine. According to
Dr. F. T. Roberts, the most prominent symptoms of a
supposed bilious attack are anorexia, furred tongue, a bitter
taste, sickness, constipation, and headache, with a feeling of
marked depression and general malaise. However such
attacks may be designated, everyone knows, at least, what is
meant by a bilious attack ; and although the liver may have
little or nothing to do with them, yet they have from the
earliest history of medicine been associated with biliary
derangement, and as such they are still popularly regarded.
Irrespective of their causation, there can be no doubt that a
predisposition to them is frequently inherited, a fact which
is demonstrated unmistakably in every-day practice. So far
as I know, this is the only case in which temperament may
be confounded with diathesis ; but as the former term does
not imply any proclivity to disease, we may assume that
those predisposed to bilious attacks have inherited a con-
stitutional peculiarity which might be more aptly described
as of the nature of a bilious diathesis, owing to intensification
during transmission. However we may map out the
differences between families or individuals, a certain amount
of elasticity must be allowed, as they cannot be regarded as
hard and fast lines. Thus when we employ the terms —
temperament, diathesis, idiosyncrasy, etc., to designate
certain classes of individuals, we must remember that no
individual can be regarded as a pure unmixed type of either
sub-division : no arbitrary line may be said to divide the one
from the other, although heredity and variability are the two
laws to which they are all subject, and from which all
individual differences arise. The above terms can only be

regarded as indicating in broad characters the sum of certain
types of individual differentiation, and for all ordinary
purposes they are explicit enough, as they are easily under-
stood, and without embodying the whole truth, are yet
verified by experience. At the same time, it must not be
forgotten that every individual presents such a mingling of
temperaments, diatheses, etc., that for anything beyond the
broadest outlines we must seek still deeper, and further
backwards into the long descent of constitutional peculiarities.
Whether this bilious predisposition be included under the
name of temperament or of diathesis, or of both combined,
the fact is, that instead of being as much a distinct type as
the other diatheses, it is often rather a modification of,
or co-existing with, others. Thus it is frequently associated
with the gouty or strumous diatheses, and with the nervous
and lymphatic temperaments, and, as Dr. Milner Fothergill
says, to recognise such combination in practice, and in the
selection of remedial agents, is often more practically
useful than an elaborate physical diagnosis, and is especially
useful when physical diagnosis is not readily attainable.
Whether also the liver, stomach, spleen, pancreas, intestines,
or nervous system, be primarily involved in the production
of those attacks usually denominated " bilious," the fact is,
that they depend, as a rule, upon constitutional peculiarities
of viscus, tissue, membrane, cell, vessel, or nerve, which
evidence a predisposition, not only inherited, but also
transmissible. I have known cases in which these so-called
bilious attacks have characterised parents and children
through several generations, and the same fact has doubtless
been frequently observed by others ; and, curiously enough,
I have seen individuals in whom the bilious temperament
seemed to preponderate, but who had never experienced a

172

bilious attack in their lives. These and similar anomalies
indicate the imperfections of the most scientific grouping of
the differences between man and man, but like the ideal
law of heredity which is never attainable, these groupings,
if necessarily imperfect, are yet satisfactory enough to merit
the recognition of experience in the present light of scientific
inquiry. Like all other sub-divisions of natural laws, they
consist of groups of phenomena which, however imperfect
or incomplete in detail, are yet sufficiently capable of
indicating their dependence upon the parent law as to
demonstrate its existence, and in what direction we must
seek for the causes of which they are the effects.

When alluding to the temperaments, I was careful to
define the term as " applicable to the sum of the physical
peculiarities of an individual, exclusive of all definite ten-
dencies to disease," as no special proclivity is involved by
them, and stated that they ought to be regarded as merely
physiological peculiarities forming a part of the original
organisation of the individual. To the original four tem-
peraments— viz , sanguine, nervous, bilious, and lymphatic,
Dr. Laycock added two more — viz., the phlegmatic and
melancholic ; but of these, I agree with Mr. Hutchinson,
in regarding the bilious and the melancholic as simply
different degrees of the same thing, and that, as life ad-
vances, the one is very apt to pass into the other ; moreover,
that the distinguishing feature in both is one which concerns
disease rather than temperament, and which might be more
conveniently known as the hepatic diathesis. For, as Mr.
Hutchinson continues : " It is the proneness to disordered
function on the part of the liver, its ready and frequent occur-
rence, which for the most part stamps peculiarity on both these
so-called temperaments. Further, it is much to be doubted

173

whether this facility to hepatic disturbance would be found
in association exclusively, or even generally, with any
particular cast of the features, or recognisable peculiarities
in the general frame." Be this as it may, it appears absolu-
tely necessary that we should recognise a hepatic diathesis^
the possession of which is usually characterised by oft-
recurring attacks of biliousness, and that like the majority,
if not all, of the diatheses, this also is hereditary. It is thus
advisable to distinguish between the bilious temperament
and the bilious or hepatic diathesis— the former being a
question of physiology and race, if not of diathesis also ;
the latter signifying an easily recognised morbid proclivity,
which is pathological and unquestionably hereditary.

I have now considered the principal degenerative diseases
and functional derangements of the liver, with a view to
tracing the influence of heredity in each, and we have seen
in the degenerative forms of disease referred to, that they
each depend upon a pre-existing disposition which is con-
stitutional, and may be transmitted from parents to children,
or from one generation to another. We have also seen that
the various functional disorders of the liver are subject to
the same influences. In the cases of some of the diseases
and derangements alluded to, the evidence may not be so
strong as in those of others; but in making, so far as I
know, the first attempt to show that the pathological pro-
cesses, no less than the physiological and psychological
processes in man are subject to heredity, and in viewing for
the first time the entire field of human diseases with that
object, some allowance should, I think, be made, if I have
been unable to prove my argument in every case alike,
especially as the entire subject is comparatively new and
hitherto unworked. Here and there the evidence is positive

174

enough; in other cases it may seem neutral, or even negative;
but I feel assured that the more attention is directed to the
systematic and painstaking accumulation of facts, the more
will the positive and confirmatory evidence increase, and the
more plainly will it be revealed that, as our bodies and minds
are dependent upon heredity, so also does a predisposition to-
the diseases of both depend upon this great law of our being.

Diseases of the Locomotive Apparatus. — In this group are
included the rheumatic affections of the joints and muscles ;
also those other disorders generally associated more or less
with rheumatism — gout, arthritis deformans, rickets, and
mollities ossium.1

In considering the influence of heredity on this group of
diseases, I shall at once refer to that feverish constitutional
malady known as acute rheumatism (polyarthritis rheumatica
acuta) without staying to discuss how the progress of morbid
anatomy, and the comparative perfection of our diagnostic
methods, in these latter days, have restricted the domain of
ancient "rheumatism" — a term which once denoted far
more than it does now. I think I need have no hesitation
in stating that a predisposition to acute rheumatism is
distinctly and emphatically hereditary, and that it tends to
run in families : indeed, some recent observations on the
transmission of a predisposition to this affection, by Fuller,
Lebert, Picot, and other authorities, prove incontestable
that the inheritance of such a predisposition is of very
frequent — if not of invariable — occurrence, in those cases
which are not acquired. In the case of rheumatism, this
inheritance, says Maclagan, seldom declares itself before
fifteen, and is generally lost again after fifty. What is trans-
mitted is not the disease, but a tendency to it — a greater or
1 Ziemssen, vol. xvi.

less liability to contract it : that peculiar condition of the
tissues of the motor apparatus which renders them a fitting
nidus for the propagation of the rheumatic poison. He
continues, "That some peculiar condition of the motor
system is handed down in rheumatism, we know. That
this condition declares itself by a special susceptibility of the
tissues of the motor apparatus to the action of the rheumatic
poison, we also know — but more than this we cannot say —
for in this, as in all other cases of hereditary transmission,
we can only indicate, not explain, the fact." Acute rheuma-
tism is one of those diseases, an attack of which so affects
the tissues of the motor apparatus as to render them
peculiarly susceptible to further and more aggravated
attacks ; so that, cateris paribus, the more strongly the
rheumatic habit is thus developed, the more potent will be
the influence of heredity in its transmission. The real
nature of the rheumatic poison is still sub judice ; but what-
ever revelations science may yet make as to this interesting
question, there can be no shadow of doubt that a predis-
position to acute rheumatism is recognised by experience ;
also that this predisposition is indubitably and strikingly
hereditary.

It may be regarded as an axiom that the more a disease
is constitutional, the greater will be the influence of heredity
in its transmission ; we can, therefore, easily understand
why there should be some doubt as to whether chronic
articular rheumatism is hereditary or not, being essentially a
local affection. Bearing in mind, however, the fact that the
majority of those who suffer from it, have already in earlier
life undergone an attack, or attacks of acute rheumatism,
and that the former affection is almost exclusively confined
to the latter half of life, it certainly seems as if it were a

i76

sequela of acute rheumatism (which generally attacks pre-
disposed persons), and if, as is admitted, this predisposition
is transmissible, there seems no reason to doubt that to
some extent, at least, a predisposition to this sequela may
also be inherited. All constitutional affections, unless
neutralised by circumstances, as marriage into a new stock,
must be inherited in some form or degree ; but it is not
necessary that the inheritance transmitted to the child
should be exactly alike, or assume the identical form
characteristic of his parent. I have already referred to
metamorphoses in transmission, which account for such
facts as the scrofula of one generation becoming tubercle in
a subsequent one, or cancer alternating with tubercle or
scrofula : we must not on this account deny the potency
and efficacy of heredity, which is the rule, however individual
peculiarities may differ, but rather believe that, despite such
metamorphoses and dilutions which we may not be able to
understand or appreciate, the law of heredity is inexorable,
and like all other natural laws its potency can never be lost.
In this way we may account for the fact of a constitutional
affection like acute rheumatism — or rather a predisposition
to it — being inherited, whilst the effects of heredity are less
potent as regards one of its local sequela^ chronic articular
rheumatism. That any one, however, who has inherited a
predisposition to acute rheumatism, subsequently surfers
from it, and later on in life develops chronic articular
rheumatism, can in turn transmit a predisposition to the
one, without, at the same time, transmitting some suscepti-
bility to the other — however diluted or whatever form it may
assume, I, for one, cannot admit. The one thing we have
to remember is that heredity is the rule ; that, however, it
may be altered by circumstances in form or degree, its

177

efficacy still exists, and this, notwithstanding the fact that we
may not be able to recognise it. I therefore contend that
chronic articular rheumatism being most frequently a sequela
of acute rheumatism, and a predisposition to the latter
being transmissible — that although the latter is constitutional
and the former local, they stand towards each other as cause
and effect, and consequently a predisposition to the one
must include to some extent a predisposition to the other.
In the same category may be included myalgia, lumbago,
etc., which, whether dependent on inflammatory changes in
the muscular or the interstitial connective tissue, or neuro-
pathic conditions, are decidedly hereditary, as is proved
by every-day experience. I have myself known families,
members of which have suffered from attacks of lumbago
in one generation after another, and we have all seen the
same thing occur as to rheumatic cephalalgia, intercostal
rheumatism et hoc genus omnt.

In approaching the consideration of the heredity of gout,
I am fortunately assailed by neither doubt nor difficulty, as
in the vast majority of all cases of gout, it occurs in con-
sequence of an inherited predisposition, and this is admitted
by all authorities. Out of 523 gouty persons, Scudamore
found that 309 had come from a gouty stock ; Gairdner, 140
out of 156 ; Garrod 75 per cent. ; and Braun, out of his
sixty-five patients, did not find one whose parents or grand-
parents had not suffered from the disease. Dr. Garrod, in
his classical work on " Gout and Rheumatic Gout," instances
the following cases : — " A few years since, I was consulted
by a gentleman labouring under a severe form of gout, with
chalk-stones, and, although not more than fifty years old, he
had suffered from the disease for a long period. On inquiry,
I ascertained that for upwards of four centuries the eldest son

of the family had invariably been afflicted with gout when
he came into possession of the family estate." He also
relates the following case, which illustrates the terrible
influence of heredity in connection with the disease now
under discussion : " A gentleman, forty-eight years of age,
whose health has been good with the exception of attacks
of gout, which commenced at the age of thirty-six in one
great toe. The attacks gradually became more frequent,
and more prolonged, so that he was scarcely ever free from
them." Dr. Garrod thus sums up the hereditary influence
in this case : " The father had very severe gout, the mother,
when seventy years of age, began to suffer from it ; he has
had six bi others, of whom one died of very severe gout,
and was crippled from chalk deposits in both upper and
lower extremities ; another had severe gout and chalk-stones,
and died of albuminuria ; a third had gout and paralysis, of
which he died ; a fourth had gout, and died of erysipelas ; a
fifth died of gout, complicated with some urinary affection ;
and a sixth is alive, but suffers from gout in the same way as
the patient himself." Gout occurs much more frequently
in men than in women, who seldom suffer from it until
after the menopause ; the predisposition is, therefore, more
frequently inherited from the father's side, than from that
of the mother ; moreover the tendency may often be traced
to the grandparents, while the parents themselves remain
free, especially if they have been careful to avoid the exciting
causes of the gouty attacks. Heredity also influences the
time of life at which the gouty paroxysms supervene ; thus,
in those persons who have an inherited predisposition, the
attacks come on at an earlier period than those who have
an acquired tendency ; in the latter, gout usually makes its
first appearance between thirty and forty, but in those

179

hereditarily predisposed it may manifest itself at a much
earlier period. Gout is not only a very serious malady in
itself, but may become the parent of grave constitutional
and functional disorders and diseases. Of these the following
may be here enumerated — viz., of the digestive organs :
gastritis, neurotic disturbance, dysphagia, intestinal colic,
diarrhoea, and hepatic derangement ; of the nervous system :
headache, vertigo, mental disturbance, delirium, mania,
epilepsy, neuralgia, cramp, local paralysis, meningitis; of
the heart : slow, rapid, weak, irregular, or intermittent
action, syncope, collapse, and various painful and disagree-
able sensations ; of the lungs : asthma, bronchial catarrh,
and pulmonary congestion ; of the urinary organs : chronic
cystitis, urethritis, gravel, and calculi. In addition to the
foregoing, there is also the terrible haemophilia, now regarded
as a result of gout ; apoplexy due to rotten blood-vessels ;
and the cirrhotic, fibrotic, or gouty form of Bright's disease.
In this extensive category might also be added eczema and
various other forms of skin disease.

We thus see how compound and complex is the inheritance
of gout in all its terrible totality ! A typical case of gout,
whether inherited or not, is easily recognised, and that
it is generally hereditary is freely admitted ; but when we
see, as experience leads us to expect, severe digestive,
nervous, cardiac, pulmonary, and genito-urinary symptoms
developed in gouty subjects, we should regard them as
revealing symptoms, and remember always that these, too,
may be perpetuated hereditarily, either in similar or dis-
similar forms, in accordance with the law of variability —
one series of the phenomena of which is represented by the
so-called metamorphoses in transmission. Taken either singly
or together, all these symptoms reveal the gouty diathesis

i8o

which is strikingly hereditary, so that in their production
heredity is always not only a potent, but an inevitable
factor wherever they exist or may co-exist. No one who
has ever suffered from gout is incapable, c&teris paribus, of
transmitting a tendency to some of its protean forms to his
children, and although in each case it may manifest itself
differently, yet it should never be forgotten that heredity
and variability are the two sources of the tissue proclivities
which attest the inherited taint of gout in every case.
Heredity, in .fact, necessitates the transmission ; variability
is accountable for the degree and variety of the inheritance.
Rheumatic gout, or rheumatoid arthritis, may be said to
bear the same relation to gout as chronic articular rheumatism
does to acute rheumatism or rheumatic fever; although it
may occur in persons who have never suffered from either
gout or rheumatism, whilst generally presenting evidences of
both, especially in its external characteristics. The pathology
of rheumatoid arthritis is still a qucestio vexata. Dr. Fuller's
views are as follows : " The disease should not be regarded
as of a hybrid character, or, in other words, made up in
part of rheumatism, in part of gout. It is my firm convic-
tion that, just as true rheumatism and true gout do both
manifest themselves at different periods of life in the same
individual, so rheumatic gout may arise in a person who
either has been, or may hereafter become, subject to true
rheumatism, or true gout, and that it has no connection with
either of these diseases, beyond that which attaches to it in
virtue of its being a constitutional disorder, producing local
manifestations in the joint." As Sir Alfred Garrod, however,
naively remarks : " It is a much easier task to prove what
rheumatoid arthritis is not than to give the slightest clue to
what it is." Irrespective of its pathology, I am more

concerned with the hereditariness of a predisposition to it ;
and although it must be admitted that the influence of
heredity is less potent than in that of gout or rheumatism,
yet I maintain that like all other constitutional conditions,
however they may be modified in transmission, a predisposi-
tion to rheumatoid arthritis is transmissible, and this in the
face of much opposition. Thus Garrod says : " Hereditary
tendency does not appear to exert any very special influence ;
for in looking over the histories of numerous cases, I fail
to find much evidence of its action ; if it exists at all, it is
much less powerful than in gout. We often find one
member of a large family suffering severely from this disease,
and the others entirely free from it." Now the great
authority from whom I have just quoted does not deny that
it is hereditary to some extent, but admits that the hereditary
tendency is less powerful than in gout. I also admit this ;
but until the question is settled as to why some morbid
affections should be so much more strikingly hereditary
than others, we must be content with the fact that such is
the case, and rely entirely upon the light afforded by an
ever-increasing experience. That experience warrants our
belief in the hereditariness of rheumatoid arthritis is
evidenced by the testimony of Professor Charcot, who, in
forty-one cases, found a hereditary predisposition well
marked in eleven. Moreover, Garrod strives to strengthen
his negative testimony as to the hereditariness of this disease
by instancing the fact of one member of a large family
suffering severely from it, whilst the others remained free !
May I venture to ask if all the children of phthisical,
scrofulous, or even gouty parents, have these predispositions
transmitted to them in the identical forms, and in similar
degrees, as those existing in the parents ? Surely not ; else,

l82

indeed, should we be able to witness the realisation of the
ideal law of heredity ! The fact is that variability or atavism,
however mysteriously, pre-determines which children shall
be affected, and in what degree, or whether, whilst they
themselves may entirely escape, they may have the inherited
predisposition enshrined within them, inoperative, ineffective,
and inactive, so that they, in turn, may transmit it to their
children, and their children's children. May I also ask, how
came one member of the family, alluded to by Garrod, to
be suffering from the disease ? Did he inherit or acquire it ?
If the former, he will undoubtedly pass on a predisposition
to it more or less ; if the latter, he may also transmit it,
even in an aggravated form. Heredity works in larger
cycles than we are apt to give it credit for ; for beyond the
parents and their children are their ancestors and their
descendants for many generations, and even as the past
slumbers in each one of us, so do the sanitary welfare and
happiness of our children's children in the future, for
heredity governs all, and its force is never lost.

When alluding to the rachitic diathesis, in an earlier
portion of these papers, I said that authorities were divided
as to whether it was hereditary or not, also that the
majority seemed to think that it was not. At the same
time I admitted my belief that the general condition of
the health of the mother had much to do with a predis-
position to rickets in her children, provided her health was
low and poor. To this opinion I still adhere, although
time and circumstances impel me now to favour the views
of those who regard rickets as hereditary whatever may be
said as to the hereditariness of the diathesis. At least in
numerous cases of rickets, hereditary influence has been a
factor of great importance, especially manifesting itself in

a predisposition inherited more frequently from the mother
than from the father; moreover, it has frequently been
observed that when several families have resided under
the same roof, and under similar circumstances, none of
the children became rickety except those whose fathers or
mothers had suffered from rickets during their childhood.
Besides, as a further evidence of an inherited predisposition,
numerous cases of fcetal or congenital rickets have been
observed under circumstances which negatived the possibility
of any syphilitic or placental influence. As shewing
metamorphoses in transmission, I may mention the fact that
other constitutional diseases in the parents may contribute to
the production of rickets in their offspring ; thus Ritter von
Rittershain alleges chronic tuberculosis in the father as a
predisposing cause of some importance. Among the parents
of seventy-six rickety children whose family history he
investigated, he found seven tuberculous fathers and four
tuberculous mothers. In the same way many facts are
forthcoming to support the opinion that constitutional syphilis
in the parents also predisposes to rickets in the clildren,1
and thus heredity acts, mysteriously and potently with
variability, acts and interacts, preserving and perpetuating
the commonhealth of the community, as it preserves and
perpetuates the characteristics of the race by varying and
differentiating the individual.

Of the remaining diseases of the locomotive apparatus, I
have still to refer to that very rare disease, osteo-malakia or
mollities ossium, which has also been termed " rickets of the
adult." Alluding to this, Mr. Hutchinson says — "Respecting
a certain number of the best marked cases, there appears
good reason to believe that the disease is really a form of
1 Senator.

184

rickets, and that the differences observed between the two
maladies are chiefly due to the very different condition of
the osseous system as regards its development at the time of
attack." Facts are forthcoming which support this view;
thus Trousseau records a case in which osteo-malakia attacked
a woman of seventy, who had been rickety in childhood.
Mr. Hutchinson also mentions a case (the skeleton of which
is in the Brighton museum) where the man had lost two feet
of his stature from innumerable fractures, faulty union, and
the bending of his bones. The children of this man were
much deformed by infantile rickets. As to the identity
of osteo-malakia with rickets occurring at a later period of
life, and the heredity of both, with regard to the former it
should be remembered that the rachitic diathesis is dependent
upon defective diet and absence of warmth and sunlight ;
that, as a general rule, it is only temporary, existing no longer
as soon as the defective surroundings and diet are supplanted
and neutralised by warm, dry, pure air, sunshine, and judi-
cious dietetic treatment. Yet it is probable that in the few
rare cases of mollities ossium which occur, it may have been
reproduced, or developed de novo, under circumstances
similar to those on which its primary production depended.
Be this as it may, there is much in common in rickets and
mollities ossium for which the rachitic diathesis satisfactorily
accounts ; and when we remember that both spring from and
are perpetuated by constitutional conditions involving
defective nutrition, we need have no hesitation, especially in
the light of the affirmative evidence recorded, in regarding
both affections as transmissible by heredity.

General Disorders of Nutrition. — The series of disorders
which I now propose to consider may be regarded as
entirely constitutional, and, therefore, all the more likely to

be hereditary. It must be admitted that there are different
types of physiological constitutions manifested among
various healthy individuals ; yet so elastic and indefinite are
the characters by which these are distinguished, that every
degree and variety of transitional forms are frequently
manifested. In the same way, no hard and fast line of
demarcation can be laid down as dividing purely physiological
from pathological conditions, and as even health itself is an
arbitrary relative condition, so physiological phenomena
merge imperceptibly into those which are pathological. In
this group of constitutional disorders " the stability of the
dynamic equilibrium of the vital processes is different from
that which subsists in health — depends immediately upon
the morbid change which the vital processes have undergone
in regard to their force and direction, and is, therefore,
ultimately bound up with the very essence of every constitu-
tional disorder." It is quite possible that an individual
suffering from one or other of these nutritive disorders may
for a long time appear in excellent health, until, in fact,
some critical epoch, or external influence, or some inter-
current malady will develop the morbid tendency into a
well-marked pathological condition. In the production of
these, as in that of other, diseases or disorders, two sets of
causes are usually recognised — viz., external or exciting, and
internal or predisposing. Of the former we must be careful
to exclude, in general terms, those of an infective or toxic
character, from those denominated " autogenetic," which
may be said to consist in some deficiency, unsuitableness,
or excess of the normal vital stimuli, as light, air, warmth,
food, exercise, etc.1 Of the internal or predisposing causes,
which influence the development of the general disorders of
1 Immermann.

i86

nutrition, I may mention in the first place, as of most
importance, inheritance; then age, sex, physiological con-
stitution, errors of development and pathological processes,
and psychical influences. Of these I am more concerned,
on the present occasion, with inheritance, the influence of
which is so emphatic and unmistakable as to often render
all other possible causes as of no account. It should be
remembered that hereditary constitutional maladies may be
indiscriminately inherited from either parent, but that when
both parents have the power of transmitting the same con-
stitutional condition or anomaly, the transmission becomes
almost absolutely certain. Heredity is the rule ; non-
heredity the exception. The exception may be illustrated
by the following facts : — The influence of an affected parent
may be neutralised or rendered dormant by that of the
other one : by atavism or reversional heredity a whole
generation may be passed over, the inherited influence
reappearing as potently as ever in the next : some members
of a generation may be affected, others spared, owing to the
influence of one parent being transmitted to certain mem-
bers, whilst that of the other is transmitted to others, or
that of fathers to sons, of mothers to daughters, or of
fathers to daughters, and of mothers to sons. As Immer-
mann says : " The parents need not always exhibit visible
signs of their constitutional vice at the moment of concep-
tion : a general disorder of nutrition which is latent in them
is as capable of being transmitted as one that is apparent.
The inherited vice often remains latent in the infant, and
does not show itself until a later period — till the age at
which it showed itself in the parent. Hence, it follows that
age as well as sex may favour or oppose the influence of
heredity ; that it is more correct to speak of the constitu-

187

tional vice itself, than of its manifestation, as being subject
to inheritance." By the general law of heredity is therefore
meant, that the most essential qualities of the parents are
transmitted to their children, unless neutralised by other
internal or external influences, and this law affects alike the
domain of physiology and of pathology. Children resemble
their parents, not however, " as stiff copies of equally rigid
prototypes, but as variable magnitudes whose variations
obey the same type." From this it will be seen that it is the
entire physical life which is reproduced — the constitutions
of the parents, with all their natural changes, which are
generally transmitted : and so, even as a normal constitution
is transmitted, is a constitutional vice repeated in the
offspring.1

I shall now consider some of these general disorders of
nutrition with regard to their inheritance.

Anosmia — Different persons have relatively unequal
quantities of blood, and different persons are differentiated
still further from each other by relative differences in the
state of physical nutrition. Healthy constitutions may,
therefore, be divided into those which are rich in blood
or vigorous, and those which are spanaemic or feeble,
according to these two sets of phenomena. When it is
remembered that an individual constitution is the result of
heredity, and the influences of his environment during
fcetal and extra-uterine existence, it will readily be con-
ceded that certain forms or types of weakly, feeble consti-
tutions, which so frequently develop pathological anaemia,
are often inherited from either or both parents. The fact
of whole families being characterised by a predisposition
to anaemia in its many forms is proof enough. How
1 Ziemssen.

i88

frequently is this the case ! And there cannot be a shadow
of a doubt that whether we regard "the average power of
renewing the constituents of the blood, the average rapidity
with which they are utilised in nutrition and growth, and
finally, the average amount of the blood store (as the
resultant of the first two elements)," they are singly and
collectively subject to the influence of heredity. The
exciting causes of anaemia are numerous and important :
but whether we regard the affection itself in its physiological
or pathological aspect, we find in one as in the other almost
invariably a predisposition which is inherited more or less,
in differing degrees, and that the physiological predisposition
will very readily become developed into the pathological.

Chlorosis. — To the influence of certain predisposing
causes inherent in the patient's constitution we must trace
the source of chlorosis ; and these are principally — sex,
age, and heredity, which have the greatest share in its
development. Sex and age are, in this affection, of pre-
eminent importance, inasmuch as no combination of causes
from which these are omitted are competent to develop it.
In fact, youth and the female sex are indispensably necessary.
With regard to age, chlorosis usually affects young girls
between the ages of fourteen and twenty-four, during the
time when sexual evolution occurs. Of no less importance,
however, is the influence of heredity, as an inherited pre-
disposition must be admitted to exist in many, if not the
majority of cases. Moreover, the heredity of chlorosis may
be taken as an example of certain inherited affections which
usually manifest themselves at the same period of life at
which they affected parents or ancestors, and which have
been explained on the hypothesis of latent characteristics
contained in the individual in the germ state, and which

189

come to light only under definite conditions, and at some
particular point of her or his development, and this par-
ticular moment corresponding with a similar moment in the
progenitors. Hereditary diseases are, in fact, good instances
of heredity at corresponding periods. Thus chorea, which
usually makes its appearance in childhood, chlorosis in
youth, consumption in middle age, gout in old age, are
naturally hereditary at the same periods. With regard to
the inherited tendency to chlorosis, the disease is often
found breaking out in the majority of, or in all, the female
members of a family from one generation to another, oft
repeated, and at corresponding periods of life, and this inde-
pendent of the external circumstances amid which they may
have been brought up. Previous to the development of the
•chlorotic attack, predisposed girls have usually manifested
anaemia, and functional irritability of the nervous system,
but not invariably, as the attacks have been known to occur
unexpectedly in seemingly robust and healthy girls. In
•whatever way produced, however, and under whatever
circumstances, there is in the generality of, if not in all
cases, a predisposition which is potently and emphatically
hereditary.

Progressive Pernicious Ancemta. — I only allude to this rare
.and mysterious affection in order to make the list of affec-
tions now under discussion as complete as possible.
Unfortunately, so little is known as to the etiology or
pathology of this morbid condition that I am unable to
furnish any evidence as to whether it can be said to be
hereditary or not. Closely allied in kind to ordinary idio-
pathic or symptomatic anaemia and severe chlorosis, it yet
differs materially from either in degree, and is characterised
by the so-called " anaemic fever " of Biermer, which,

igo

cazteris partbus, may be regarded as, to some extent, patho-
gnomonic. Frequently associated with pregnancy, this
almost invariably fatal condition sometimes occurs as a
complication during ordinary anaemia, but the causes of
such complication are completely unknown — as, indeed, is
almost everything concerning either its etiology or pathology.
At the same time, as it is closely allied to anaemia and
chlorosis — which, as we have seen, are both hereditary —
I cannot abandon the idea that in some cases, at least, there
is an hereditary element in its production ; there can, at any
rate, be no effect without a cause, and as the causes of
disease are either inherited or acquired, I shall at least
maintain the hypothesis of heredity, until it can be proved
that this mysterious condition is dependent entirely upon
external circumstances for its causation.

Corpulence or Obesity. — It must be admitted that a predis-
position to this condition is generally either inherited or
congenital, and this despite all other causes that can be
assigned. Those who are predisposed will become fat under
any circumstances, and in any rank or condition of life.
Like most hereditary constitutional anomalies, its transmis-
sion consists in a tendency only, and it may also be included
amongst those affections which occur at corresponding,
periods of life. Thus it may occur during infancy, or not
until the fortieth year or thereabouts, and later. It has not
yet been determined whether sex has any influence on the
hereditariness of this affection, or whether the male or female
parent has most to do with the transmission of the tendency,
It is more than probable, however, that the predisposition
more frequently descends from and to the same sex — viz.,,
from father to son, and from mother to daughter.

Immermann, in discussing the peculiarities of constitution
upon which the inherited corpulence can depend, enumerates

the following — viz., hereditary differences in the rapidity of
blood formation, dependent upon the new growth of red
corpuscles ; hereditary differences in the trophic and plastic
energy of the other tissues of the body ; and hereditary
differences in the quantity, function, and proliferating capa-
city of the fat-carrying connective tissue and its vascular
apparatus. The foregoing are some of the conditions which
on the one hand influence the extent of the tendency to fat-
production ; and, on the other hand, possibly or certainly,
come under the influence of the hereditary principle. Thus
far Immermann analyses the constitutional peculiarities on
which, in a pathological sense, corpulence depends ; but it
will be seen that they are all hereditary, and this is the main
point for which I am contending. There cannot, indeed, be
any doubt that obesity is a condition, a tendency to which is
unquestionably hereditary, and that it characterises families
for successive generations malgre many systems of treatment
and innumerable nostrums, notwithstanding which natura
non nisi parendo vincitur.

Scrofulosis. — However great the temptation, I have no
intention of entering here into a discussion of the
innumerable theories propounded from time to time as to
the etiology and pathology of scrofula, and its relation to
tuberculosis, but shall content myself by observing, in the
words of Dr. H. G. Sutton, that " A strumous constitution
produces phthisis ; scrofula and phthisis are inseparable."
Regarding tuberculosis or scrofulosis as a constitutional
disease, it is now universally acknowledged to be hereditary
in its origin. Pathologists are divided in their opinions as
to whether the disease itself, or a predisposition to it, is
inherited; and, notwithstanding the fact that tubercle is
often actually congenital, I am inclined to believe, with

I92

Niemeyer and his school, that as a rule, only a constitutional
debility is transmitted, with a tendency to low forms of
inflammation, the products of which rapidly become caseous,
and thus lead to tubercle. My own opinion is that a pre-
existing condition of scrofula is, in the majority of cases,
necessary for the development of tubercle, although what is
recognised as scrofulous does not always attain a distinctly
tubercular condition. In tubercular as in scrofulous cases,
there will usually be found a predisposing as well as an
exciting cause — the former being hereditary, the latter
acquired ; and the higher the degree of hereditary pre-
disposition, the less need there will be for an exciting
cause.

Following closely the definitions of Virchow and Billroth,
Birch-Hirschfield thus defines scrofulosis : — A constitutional
anomaly which shows itself by changes, partly of an inflam-
matory, partly of a hyperplastic nature, excited in the tissues by
a comparatively slight noxious influence — changes which are
endowed with insufficient recuperative power, and are there-
fore prone to lapse into regressive metamorphosis, and
following thereupon, into local tuberculosis. Virchow ascribes
scrofulosis to " a certain weakness or incompleteness in the
structure of the lymphatic glandular apparatus," and accept-
ing this theory as far as it goes, we should remember that
pathology furnishes us with many proofs as to the dependence
of weakness of certain systems and organs on an hereditary
predisposition. Thus haemophilia furnishes an example of
inherited weakness in the circulatory apparatus. Many
other instances might be mentioned.

Of the causes which give rise to scrofulous constitutions —
apart from anatomical and physiological conditions, concern-
ing which nothing is definitely settled— the most important,

193

and that most materially supported by experience, is here-
ditary transmission. Undoubtedly various forms of scrofulous
as of tubercular disease run in families. Every practitioner
must be cognisant of the fact that the parents of scrofulous
children were themselves, in many instances, also scrofulous
in their early age, and that phthisical parents very frequently
generate scrofulous children. Although statistics may not
count for much, yet Lebert was able to prove hereditary
transmission in one-third of eighty-eight cases. Balman
ascertained that among 141 scrofulous patients nine had lost
the father, and eleven the mother, of tuberculosis ; while
thirty cases of tuberculosis had occurred in near or distant
relatives of the rest.1 It must therefore be conceded that
from first to last, amid all its sources and varieties, amid all
its developments and retrogressions, in whatever form it may
assume, amid all its degrees and complications, heredity is
the prime factor in the production of scrofulosis, as it is also
in tuberculosis.

Diabetes Mellitus. — But a few decades ago, anyone who
would have ventured to include heredity as a predisposing
cause of this affection would have probably been treated
with ridicule. Since, however, greater attention has been
directed to the matter in more recent times, the result of
constantly accumulating experience is undoubted and in-
creasing testimony in regard to the hereditary character of
diabetes. Not only have several of the brothers and sisters
in certain families become diabetic, but instances are
recorded where every child has been the subject of this
disease. Moreover, it has been frequently observed that
parents, or grand-parents, suffering from the disease, have
transmitted a -predisposition to their children and grand-
1 Ziemssen.

i94

children respectively ; nay, more, cases have frequently
occurred even among the collateral and more distant relatives
of diabetics. I feel assured that time and increased ex-
perience are alone wanting to substantiate the views held in
the foregoing pages as to the influence of heredity in the
production and development of morbid conditions generally,
and for the reasons assigned — viz., that the inheritance of
physiological and psychological peculiarities necessitates the
inheritance of those which are pathological.

Epilepsy, mental affections, and other diseases of the
nervous system are often intimately associated with diabetes,
and this connection is also, in almost every case, due to
hereditary predisposition. Cases showing the co-existence
of epilepsy, melancholia, etc., are recorded by Seegen,
Zimmer, Schmitz, and other authorities. Among the near
blood relations of a diabetic patient Langiewicz found
epilepsy in seven. One of Griesinger's patients had had
epileptic seizures in childhood, and all the brothers and
sisters had suffered, or were suffering in the same way. A
case is recorded by Lockhart Clarke, in Beale's Archives of
Medicine, in which diabetes occurred in an epileptic who
died of cerebral softening.

As to the heredity of diabetes itself, many cases are
recorded by P. Frank, Blumenbach, Brisbane, Prout, Pavy,
Dickinson, and Senator, and Marsh records the case of a
family in which the disease was transmitted even to the
fourth generation. From 1868 to 1874, R. Schmitz was
enabled to positively affirm the influence of heredity in 22
out of 104 cases.1

Diabetes Insipidus is also undoubtedly hereditary, and like
the mellitic affection is frequently associated with the neuro-
1 Senator,

pathic predisposition. An hereditary association has also
been observed between the insipid and mellitic variety.
Thus Trousseau, Reith, and Seegen report cases in which
the grandfather had the mellitic and the granddaughter the
insipid form ; a father and son had the mellitic and a
daughter the insipid form, and a son had diabetes mellitus
•whose father had suffered from diabetes insipidus. The
most remarkable instance of hereditary predisposition is that
recorded by Lacombe, in which, out of one family a mother,
three sons, and a daughter were attacked by the insipid form
of diabetes, besides the brother of the mother and his
children. Other interesting and less startling cases are
reported by Lancereaux, Deebray, Reith, Desgranges, and
Addinel Hewson.

Having thus glanced rapidly at the principal general
disorders of nutrition, it will be seen that heredity has a large
share in their production ; and although in some instances
the testimony recorded may be less satisfactory than in
others, yet I firmly believe that in the future, and probably
before long, increased experience will not only attest the
views I have enunciated, but will throw the light of science
over that which may now appear be be vague and
hypothetical.

Acute Infectious Diseases. — These are now generally classi-
fied as follows — viz., I. Contagious: including measles,
scarlet fever, variola, vaccinia, typhus, diphtheria, glanders,
malignant pustule, rabies, virulent ulcers and blennorrhceas,
syphilis, pyaemia, puerperal fever, and erysipelas ; II. Mala-
rial or Miasmatic : including simple intermittent, remittent,
and continued malarial fevers, etc.; III. Miasmatic Conta-
gious diseases : as cholera, typhoid, dysentery, yellow fever,
plague, influenza, hay fever, miliary and Dengue fevers, and

196

epidemic cerebro-spinal meningitis. Are these, or any of
them, subject to the influence of heredity ? Before attempt-
ing to answer this question, I may be permitted to mention
the now generally-believed doctrine that the acute infectious
diseases are dependent for their production upon a contagium
or miasma vivum ; in other words, upon specific germs which
have the power of reproducing themselves to an unlimited
extent, the specificity of which consists in the fact that a
given form or kind of disease is invariably, absolutely, and
under all circumstances, due to a given kind of morbific
germ, as cause or agent. We thus see that — at any rate, in
the majority of the acute infectious diseases — the body
remains passive to the action of germs, virus, or poison
intruded from without ; and that the autochthonous origin
or spontaneous generation of the contagium vivum is no
longer generally recognised or admitted. When we therefore
regard the fact that any of these specific germs or poisons
may so disturb the health of an infected individual as to not
only cause him intense suffering, but to jeopardise his life ;
that after a longer or shorter time these effects may cease
completely, and, beyond the life-long immunity from the
influence of the same poison thus produced, the body may
be otherwise unmodified, we cannot expect to find much
evidence of the influence of heredity, especially as even the
immunity of the individual cannot be transmitted to any
great extent. Doubtless, these specific fevers, or, at least,
some of them — as, for example, measles and small-pox —
may occasionally aggravate a pre-existing diathesis as the
tubercular or scrofulous, or may produce ephemeral dyscratic
conditions of health ; but as a rule, after the cessation of
the specific exanthem or fever, the bodily organs and func-
tions may remain unaffected, so that beyond the passing

i97

effects of a more or less sharp specific attack, the physical
and mental condition of the individual may return to their
original state. Not always, however, is even the immunity
of the individual from modified, or even full-developed
secondary attacks, complete, as either may recur repeatedly,
so that it may be safely said that no heritable condition of
health is ever produced.1

Having thus far stated the case against heredity, I may now
be permitted to ask — how is it, as frequently happens, that
these specific germs or poisons manifest such a selective
capacity that they may attack only one or two individuals in
a family, and leave the others unaffected ? How frequently
this happens is well known to every practitioner. While it
is quite true that a low physical condition induced by intem-
perance, bad feeding, chronic disease, over-crowding, want of
cleanliness, mental depression or fear, very often predisposes
individuals to succumb to an attack of some of the acute
infectious diseases, it must not be forgotten that there are
individuals in most families who, owing to some constitu-
tional peculiarities, are insusceptible of being influenced by
some of them, while yet other individuals are insusceptible
to the influence of other specific poisons. At the same
time it should be stated that insusceptible individuals may
sometimes act as media for the dissemination of some of the
exanthemata if allowed to pass from the sick room, and to
mingle with healthy persons. There is, in fact, not one of
these acute infectious diseases to which many individuals
are not more or less insusceptible ; and I contend that where
this insusceptibility has not been acquired by an attack of
some of the acute infectious fevers, it must have been
inherited as a constitutional peculiarity, although we cannot
1 Mr. Jonathan Hutchinson.

198

tell in what this peculiarity consists. In other words, some
individuals are predisposed to the acute infectious fevers,
whilst others are not ; and as this predisposition cannot, so
far as I know, be acquired — as the specific fevers are incap-
able of originating pathological habit by their repetition in
the same individual, and therefore are incompetent to
produce anything in the nature of a permanent diathetic
condition — it must be inherited as a constitutional peculiarity.
We thus see that while the specific fevers, in their influence
upon those affected by them, leave no taint that may be
transmitted, and that so far as the majority of the exanthe-
mata are concerned, one severe attack of either of them
confers an immunity (which may be life-long) from secondary
attacks ; yet the fact remains that in almost every family
there are those who are either especially predisposed, or
more or less insusceptible to their influence, and that whilst
such predisposition consists in an unknown constitutional
peculiarity, it is only fair to assume that it has been produced
by heredity. Moreover, unless the insusceptibility has
resulted from the immunity bestowed by a former attack,
and has thus been acquired, it may also be regarded as a
constitutional peculiarity which has been inherited.

I have said just now that one attack of an exanthem
may confer an immunity from secondary attacks which may
last during the life-time of the individual, but even this
immunity is often seen to be neither perfect nor universal ;
for there is not one of the exanthemata which may not
attack the same individual more than once, although a first
attack so modifies those which are secondary as to render
the symptoms, as a rule, much less severe, and comparatively
immature. In the case of vaccination, for example, it is a
well-known fact that while some persons lose its protective

i99

influence much sooner than others, there are others who are
insusceptible to the vaccine virus altogether. So much for
the exanthemata.

Of those acute infectious diseases which are not due to
specific animal poisons I may instance erysipelas and diph-
theria, to both of which, whilst most persons are subject to
their influence, some are peculiarly susceptible, and the
susceptibility is such that it persists throughout life, and is
unquestionably hereditary. " In both," as Mr. Hutchinson
says, " that with which we have to deal is a personal and
inherited peculiarity, giving proclivity when certain exciting
causes are brought to bear, to peculiar forms of inflammatory
action." There can be no doubt that the difference between
the states of health produced by the specific poisons, and
those which are due to inflammation from non-specific causes,
are strongly and well marked, the latter coming under the
law of intensification by habit. The same authority says :
In the development of such inflammations as those of ery-
sipelas, diphtheria, elephantiasis, and especially when not due
to contagion, the constitution of the individual takes a large
share, and the mere fact of their occurrence reveals his
previous proclivity. The disease originates in part from
without, but in part also from within. It is not an instance
of intrusion, but of development, and the peculiarities of
blood, tissue, or nervous system, are exactly those which are
capable of increase.

It is, indeed, beyond question that amongst the causes of
erysipelas and diphtheria, family and individual susceptibility
must be regarded as factors of prime importance. It would
be easy to cite cases in defence of this assertion, but as the
fact is too well known to be denied, I shall content myself
by the mere statement of it.

2OO

Of the remaining infectious diseases which are also purely
contagious I have yet to consider glanders, malignant pustule,
rabies, virulent ulcers and blennorrhceas, pyaemia, and puer-
peral fever ; these, however, being all caused by external
poisons introduced into the system, need not detain me here,
as heredity can have nothing to do with them beyond the
fact that the system into which they are introduced may have
an inherited constitutional peculiarity which will predispose
to their influence. Indeed, of this there can be no doubt,
as none of them can germinate without a suitable soil, and
in the case of each one of these affections, many individuals
seem to be especially predisposed, while others show com-
parative immunity. I may now briefly sum up the results of
our inquiry as to whether the acute infectious diseases are
subject to heredity, and if so, to what extent. I have asserted
that so far at least as the exanthemata are concerned, the
mental and physical condition of affected individuals may
remain unaltered, after the attack has subsided. Their
tissues, however, will be so far altered as to be able in all
probability to withstand a second attack of the same poison
during their lives. This immunity, however, is probably
seldom complete, and never universal. Thus these affections
leave no taint to be transmitted. On the other hand a
predisposition, or insusceptibility, is very frequently mani-
fested by those exposed to the influence of these specific
poisons, and here heredity has been a most important agent,
with the exception of those cases in which a predisposition
may have been acquired by repeated attacks (as in the case
of erysipelas and diphtheria), or in which insusceptibility
represents the immunity resulting from a first attack.

Although a chronic, and not an acute infectious disease, I
may here allude to syphilis, as it is so markedly contagious ;

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and with regard to this affection, which has been denominated
the most chronic and most persistent of all specific fevers, it
may be remembered that I did not include it in my classifi-
cation of the diatheses, and I may now be permitted to give
my reason. It may, indeed, be inferred from what I have
already said as to the non-transmissibility of any of the
effects of the specific fevers, and that this holds good also in
the case of syphilis, I think I shall be able to show. Diathesis
has been defined as "any condition of prolonged peculiarity
of health giving proclivity to definite forms of disease ; " and
referring this definition to syphilis, to which there is no
physical proclivity, we see that syphilis is more clearly a
matter of dyscrasia than of diathesis. Moreover, as in the
other specific fevers, there is no actual transmission of any
diathetic peculiarity, as, in the words of Mr. Hutchinson, " it
is not the diathesis which results from the disease, but the
germs of the disease itself— the particulate elements of the
virus — which are transmitted. It is transference, a form of
contagion rather than hereditary transmission, which occurs.
.... It is far more like contamination in utero than true
inheritance. By contamination, in this use of the word, I
mean that with sperm or germ (of either or of both parents)
there passes the virus itself, the sperm or germ being itself
unmodified, but simply the material medium of transference.
In the case of the mother we know well that it is not
necessary that the germ should have been infected at all, but
that if her blood receives the virus, even so late as the eighth
month, it will pass into that of the child also. Inherited
syphilis, when produced under these last-mentioned circum-
stances, runs exactly the same course as when derived from
a parental taint which existed before conception. A child,
then, I assert, inherits syphilis in precisely the same sense,

2O2

and in precisely the same manner, as it may inherit small-pox.
It inherits not the diathesis, but the disease. The reason
why the inheritance of small-pox is very rare, whilst that of
syphilis is, unfortunately, common, is simply that the period
during which the virus is extant in the blood is very different

in the two cases My argument, if I have made

it plain, has pointed to the conclusion that no minified
transmission of syphilis is possible ; that the child gets either
nothing at all, or the germs of the disease, and that in the
latter case they will, subject to the laws of idiosyncrasy,
develop equally in all cases." Whilst, therefore, regarding
the inheritance of syphilis as an illustration of actual trans-
ference of the germs of the disease, rather than transmission
of any diathetic peculiarities, it will be thus seen that for this
reason I regarded the syphilitic condition as one of dyscrasia
rather than of diathesis, and I thus purposely omitted it from
my classification of the latter. I therefore regard syphilis,
like the other specific fevers, as incapable to any great extent
of transmitting in the true sense any of its effects. It is
questionable whether the syphilitic virus itself is capable of
modification, and we must attribute the differences in its
results in different individuals to physical peculiarities in the
individuals themselves, some of which may have been
acquired and others inherited.

I have now to consider a group of infectious diseases
which are non-contagious, and which, depending upon
malaria as their cause, are therefore purely miasmatic.
This group includes simple intermittent and masked fevers,
pernicious fevers, remittent and continued malarial fevers,
and malarial cachexia or chronic malarial infection. These
differ from the contagious specific fevers in the following
particulars.

203

I. " Contagia are reproduced in and given off from the
system ; malaria is not."

II. " Malarial fevers are not communicable from the sick
to the healthy."

III. " Malarial fevers have an intermitting indefinite
course, and an irregular period of duration."

IV. " An attack of malarial fever confers no immunity
from a second." x

Inasmuch as each of these varieties of malarial infection
depends upon the intrusion of a poison from without, it is
not necessary for me to consider any of them in any detail.
In the foregoing pages (when treating of the diatheses) I
alluded to the nature of the malarial poison, and need there-
fore do no more than confine myself to the consideration of
how far malarial affections in general are subject to the law
of heredity. The diathesis due to malaria might almost be
regarded as universal, as few, if any, of us may be quite
exempt from its effects, however remote, inasmuch as from
the earliest times the entire human family has been brought
under its influence. This diathesis is also hereditary, the
amount of inheritance being proportionate to the intensity
and duration of the affection in the parents or ancestor. If
we remember that the subject of malaria "will display
through life peculiar susceptibilities," and that these effects
are invariably permanent, " it is easy to see that a poison so
persistent in its action and of which the effects, even in
mild cases, are so well-nigh permanent, must be capable of
producing that state of body which we call diathesis. The
malarial diathesis is, indeed, a well-marked one, and it exists
in greater or less degree in all who have ever come under
the influence of its cause."2 Thus in the pedigree of these
1 Maclagan. 2 Mr. Hutchinson.

204

malarial affections we read of their long descent, as time
alone could have rendered the human race so subject to
them, and, as a matter of fact, their history, of every type,
reaches back to the earliest period of medical knowledge.
Whilst we are all probably more or less subject to the
malarial diathesis, it should not be forgotten that all are not
in equal measure predisposed to the action of the malarial
poison, for it is well-known that " during the endemic
prevalence of malaria, only a certain number of persons are
attacked by it, the majority remaining exempt, although
subject to the same telluric and climatic influences;"1 and
this exemption is, in all probability, very frequently inherited.
That constitutional varieties are not to be ignored as influenc-
ing the liability to malaria is proved by the fact that weak and
anoemic persons are especially prone to be attacked, and,
according to Griesinger, marked differences in the character
of the disease may sometimes be recognised, according as
it occurs in subjects of a plethoric, or of an anaemic con-
stitution. As malaria can alone produce malarial diseases,
their different forms differ relatively only in degree, the
poison itself being subject to variations in quality and
quantity. These affections may, therefore, be progressively
arranged from the simplest to the severest forms as follows :
i. Quartan intermittent ; 2. Tertian ; 3. The masked inter-
mittent ; 4. Double tertian ; 5. Remittent ; 6. The continued;
and 7. The pernicious fever ; the various grades being pro-
portioned to the intensity of the poison. But the real fact
to remember is that all these varying forms are due to the
effect of the malarial poison on different individuals, and
that these individual differences may be either acquired or
inherited, and that even when acquired many of them may
be transmissible.

1 Hertz.

205

I may now summarise the evidence as to the influence of
heredity on these malarial diseases as follows : — The real
nature of the potential causative agent, malaria, is unknown :
obviously, however, it is communicated to the system from
without. Its effects differ in different individuals, but as
they have been known to exist from the most primitive
times, so they have become so inbred into the human race
that comparatively few of us are totally exempt. Thus a
diathesis has been developed which might almost be
included with those termed " universal " — viz., the catarrhal,
the rheumatic, and the scrofulous. Moreover, in addition
to this racial peculiarity, many individuals are especially
predisposed to the influence of malaria by heredity, and this
.can all the more easily be understood when we remember
that each individual who has suffered from malaria has his
tissues branded with it during his life ; and the probability
is that with the amount of diathetic peculiarity which he has
— in common with most — inherited, he will also transmit a
thus intensified personal predisposition to his children.
Given an individual who has suffered severely from any
variety of malarial disease, he must in the first instance
have himself been specially predisposed before being
attacked, and if the law of heredity holds good at all, it
assuredly follows that, c&teris paribus. he may transmit this
predisposition, if not the actual disease, to his offspring.

I have still, however, to consider the third division of the
acute infectious diseases — viz., those which may be said to
be miasmatic-contagious, which, as they cannot be conveyed
from diseased to healthy individuals by mere contact, are
not contagious according to the significance of the term, and
•on the other hand, the poison has the characteristic
peculiarity of the miasmatic diseases in being, in the first

206

instance, drawn from an external source ; but, differing from
them in the fact that " the poison only originates outside
the body when an affected body has furnished the germs. "
This division includes typhoid fever, cholera, dysentery,
yellow fever, the plague, dengue, miliary fever, influenza,
hay fever, epidemic cerebro-spinal meningitis, and, perhaps
whooping cough; and the mode of extension of these diseases
is so far understood as to enable us to state with certainty
that they can neither be reckoned among the contagious nor
among the miasmatic diseases according to the following
definition : Contagium has been defined as a specific excitant
of disease, which originates in the organism suffering from
the specific disease ; while miasm, on the other hand, is the
term used to denominate a specific excitant of disease,
which propagates itself outside of, and disconnected from,
a previously diseased organism. Contagium can be con-
veyed by contact from a diseased person to a sound one,
produce the disease in him, and then again reproduce itself.
Miasm originates from without ; taken up into the body, it
can call a specific disease into action, but it cannot spread
the disease any further by conveying it from a diseased to-
a sound person.1 Seeing then that the diseases just
enumerated are neither contagious nor miasmatic according
to the above definition, while possessing some of the char-
acteristics of both, it seems but right to include them in a
third group, to which the name miasmatic-contagious has
been given, which, moreover, they have held for a consider-
able period, though usually in another sense. As in the
two previous divisions, and for similar reasons, we can trace
no potential causative agency to the influence of heredity in
this one, apart from the fact that the protophytic fungi, some
1 Liebermeister.

207

of which have been identified as the fons et origo mail of
other diseases, are so far influenced by heredity as to always
propagate themselves after their kind, each preserving its
own characteristic individuality, so that, as Tyndall observes,
from their respective viruses you may plant scarlet fever,
typhoid fever, small pox, et hoc genus omne ; that as surely as
a thistle rises from a thistle seed, as surely as the fig comes
from the fig, the grape from the grape, the thorn from the
thorn, so surely does the typhoid virus increase and multiply
into typhoid fever, and nothing else ; the scarlatina virus
into scarlatina, and into nothing else ; the small-pox virus
into small-pox, and nothing else ; so that to all intents and
purposes a virus may be regarded as a seed which, invariably
generates after its own kind. And here we see the all-
pervading influence of heredity that necessitates its recog-
nition as an universal law, for as in the highest forms of
organic life, from man himself down through the lower
animals, until we reach the lowest forms of all, there heredity
manifests itself in the reproduction of each after its kind.

As in the two other groups of acute infectious diseases,
we find heredity acting similarly in this division — viz., with
regard to predisposition and insusceptibility. It may, indeed,
be asserted as an axiom that individual predisposition plays
an important role not only in all epidemics, but in all cases,
and it may also be stated that this predisposition, while
differing in development in different individuals, is, if not
more, at least equally, as potent as all predisposing causes of
an external character. Let me take cholera as an illustration.
It is a well-known fact that many persons enjoy at least a
temporary immunity against the disease. During an epidemic
of cholera, should choleraic diarrhoea prevail, many escape it
entirely, others suffer only lightly and temporarily, while

208

others again, notwithstanding the employment of all sorts of
therapeutical and hygienic measures, are subject to continued
and repeated attacks (Lebert). Thus, again, with typhoid
fever, the poison of which, as established by Budd, is
propagated continuously, and never originates autochthon-
ously, and which can only germinate in a suitable soil. Such
disease germs pass into each one of us every day of our
lives ; why, then, do they not manifest their specific effects ?
And why, even when they do germinate, does the product
vary? Because, in the first instance, they must become
implanted in a suitable soil, or they produce no effect, and
secondly, because when they do germinate the product
varies with the soil. Thus while some may be peculiarly
predisposed to the action of some of those specific germs,
others will be found more or less insusceptible, and that
this predisposition or insusceptibility frequently amounts to a
-constitutional peculiarity, in the production of which heredity
has had a share, it is only fair to assume. As regards the
differentiation of individuals in relation to the respective
tissue-peculiarities which they have inherited and acquired,
I cannot do better than again quote the words of Sir James
Paget, who says : " This living soil is in each as personal
and distinct as any other constituent of personal character,
and the study of it must be intimately personal, with an
exact analysis of every disposition to disease." How this
predisposition or insusceptibility is produced, or in what it
consists we do not know ; we can only accept the facts ; but
giving full force to every possible factor of an external kind,
and, in the cases of insusceptibility, to the comparative
immunity produced by previous or primary attacks,
there still remains a far greater amount of evidence as
to the efficacy of individual predisposition and insuscepti-

2OQ

bility, the result of breeding, and, therefore, of inheritance.
By this I do not mean that the parents or ancestors
must necessarily have undergone attacks of acute infectious
diseases, or that they possessed a similar predisposition or
insusceptibility towards them, but that somehow these
predispositions and insusceptibilities have appeared as
constitutional peculiarities, and that they have constituted a
life-heritage just as much as any other constitutional
peculiarity which they may have obviously inherited.

Heredity preserves the race by varying the individual, and
the law of variability, known only by its effects, is respon-
sible for this individual differentiation ; but how these
effects are produced we cannot tell, for "as one star differeth
from another," so does every individual, not only in what
he acquires, but still more in what he inherits, and further
we cannot go. It is therefore unnecessary that I should
go into any detail in considering the remaining affections in
this group — viz., dysentery, yellow fever, the plague, dengue,
miliary fever, influenza, hay fever, (undoubtedly hereditary),
epidemic cerebro-spinal meningitis, and whooping-cough.
That they are all produced by external causes introduced
into the system is an admitted fact, but that, in relation to
each one of them, some individuals are particularly pre-
disposed, while others are comparatively insusceptible must
also be admitted. That both this predisposition and in-
susceptibility may be inherited, i.e., the result of inheritance,
using the term in its broadest signification, admits but of
little doubt, and this is all I contend for. For although the
effects of the acute specific or infectious diseases leave no
trace in the affected tissues that can be transmitted to any
extent, yet it must be conceded that far beyond the agency
of external circumstances, and the relative immunity pro

210

duced by primary attacks, these predispositions and insuscep-
tibilities often amount to constitutional peculiarities in
which, somehow, heredity must have had a share in
producing. If they appear to be the result of variability,
it must be remembered that variability is necessitated by
evolution, and without heredity, evolution, nay, life and varia-
tion are impossible ; for " evolution produces physiological
and psychological modifications ; habit fixes them in the
individual, heredity fixes them in the race ;" so that heredity
and variability act and interact inseparably through the
universal kingdom of organic life and being. Thus alike in
races, families, and individuals, does heredity assert itself,
and thus are races, families, and individuals, preserved and
perpetuated, differentiated and destroyed by heredity and
variability, and as in health, so likewise in disease.

I have still, however, to consider the diseases of the organs
of special sense, and also those of the skin. To some of
the former I have already alluded in an earlier portion of
these papers, when discussing the heredity of sensorial
qualities, but as this allusion was from the psychological
stand-point, I may now be permitted to refer more par-
ticularly to the same, only from a pathological point of
view. I then showed that besides those varieties of vision
depending upon mechanical causes, those also depending
upon anaesthesia or hyperaesthesia of the nervous element
were all hereditarily transmissible. Of those dependent
upon mechanical causes, strabismus, myopia, and presbyopia
are the most common, and these are all markedly hereditary.
Portal describes the Montmorency sight — an imperfect form
of strabismus which distinguished nearly all the members
of that family. Stahl also relates the following remarkable
case : — A soldier lost in war one of his eyes. He returned

211

to his country and married ; his wife bore him a son, one of
whose eyes was quite dried up, so that he was monoculous
like his father ! Congenital blindness may run in families,
and blind persons will sometimes beget blind children. A
blind beggar was the father of four sons and a daughter, all
blind. Dufau, in his work on blindness, cites the cases of
twenty-one persons blind from birth, or soon after, whose
ancestors — father, mother, grandparents, and uncles — had
some serious affection of the eyes.1 While amaurosis,
nyctalopia, and cataract in the parents may become blind-
ness in the children, they are each transmissible, and
amaurosis, although not perhaps so frequently transmitted
as the other two affections, is yet by no means unknown.
Cataract is very frequently inherited, and Cams quotes
from Lusardi a case where the children of a man who
suffered from cataract were all born with this disease. A
remarkable case of inherited nyctalopia, which has been
strictly investigated from official documents, and described
by Cunier in a pamphlet, may here be quoted. It is shown
in this little work that nyctalopia had been propagated during
centuries in the same family, from one generation to another,
and that of 600 descendants of one ancestor, a great num-
ber were afflicted with this evil, so that the same is spread
over Vendemian and some other neighbouring places through
this family alone. There exists no example of the evil ever
having befallen a member of this family where both parents
were free of it ; whenever a child was afflicted with it, then
surely either his father or his mother had had the same
complaint. It is further proved that the complaint was, in
the greater number of cases, inherited from the father.2

1 Ribot. 2 Steinau.

212

In addition to those affections of the visual apparatus-
depending upon mechanical causes, and those abnormalities
of vision, whether of the nature of anaesthesia or hyperaes-
thesia — and which are all, in every degree, hereditary — there
can be no doubt that the majority of cases involving the
eyelids are also hereditarily transmissible, or at least that a
predisposition to them is very frequently transmitted from
parents to children. To this latter class belong epicanthus,
ptosis, entropion, ectropion, trichiasis, hordeolum, ophthalmia
tarsi, cysts, warts, and naevi. There is, in fact, no form of
ocular abnormality, whether visual or palpebral, which may
not be inherited, or to which a predisposition may not be
transmitted.

With regard to morbid affections of the ear, as in the case
of the eye, they may consist of either anaesthetic or hyperces-
thetic peculiarities, and these may be equally transmitted.
I have already discussed the heredity of deaf-muteness, and
would here only remark that it should be remembered that
in those cases in which deaf-muteness is not inherited, it may
be transformed into an infirmity of some other kind, as
hardness of hearing, obtuseness of the mental faculties, or
even idiocy (Ribot). How these transformations occur I
have already alluded to in previous pages ; moreover, in
those cases of musical talent where "a good ear " is essential,
the musical aptness necessarily depends upon the heredity
of certain qualities of hearing. Of those affections of the
ear which are perhaps most frequently inherited, I may
mention cophosis nervosa. My accomplished friend, Dr.
Macnaughton Jones, who is generally considered an authority
on every subject upon which he writes, says, in the last
edition of his excellent Practitioner's Handbook of the
Diseases of the Ear and Naso-pharynx — " That deafness is

213

one of those ailments which nature entails as a hereditary
reminder of parental imperfection is well known, and in it
frequently we have a good exemplification of the law of
atavism ; the defect appears to skip one generation and to
re-appear in the next. I have just at present a lady under
my care who is very deaf, and whose mind is beginning to
fail j she is one of a family two other members of which
are deaf. Deafness has been transmitted for generations,
and, coincident with the deafness, there is also a family
history of insanity.

Occasionally, though we cannot find evidence of deafness
in the parents, curiously enough two or three brothers or
sisters are affected. The deafness at other times will be
found on the father's or mother's side, while the parents
have escaped. Such hereditary deafness is nearly always of
a most unfavourable type, and treatment generally ends in
a negative result. In a great many cases the physician does
not see the patient until the deafness is far advanced and
there is evidence of serious middle and internal ear trouble.
. . . It is a fact, and a most vital one in regard to this
form of deafness, that we frequently find it first make its
appearance after puberty, or even later on." Thus, hearing,
of every form and variety, whether of the nature of anaes-
thesia or hypersesthesia, may have an element of heredity in
its production, which may have become decreased, inten-
sified, or otherwise modified, in its descent from one
generation to another.

With regard to heritable peculiarities of touch, I have
already referred to them when discussing the heredity of the
sensorial qualities. There can be no doubt that parents
transmit to their children the most singular perfections and
imperfections of touch ; and all these tactile sensations, as

o

2I4

hardness, softness, elasticity, etc., and sensations of tem-
perature, as of heat and cold, are alike subject to, and
governed by, the law of heredity. The relative sensibility
of different families to tickling is well known ; in fact, every
form of anaesthesia or hypersesthesia of the skin is markedly
hereditary. All this, however, is more physiological than
pathological ; but with regard to the latter I may mention
cases related by Lucas, which illustrate how the sense of
touch, when exaggerated or neutralised, ' may affect patho-
logical conditions, and how abnormal sensitiveness to heat
or cold may be transmitted. A woman whose tactile
sensibility was so exalted that for her the slightest hurt was
an agony, married a man endowed in the highest degree
with the opposite quality. He did not lack intelligence, but
his heart and his skin were impassible. A daughter was
born to them, and she is as insensible to external pain as her
father himself. We have seen her endure, without com-
plaint, and even without appearing to notice it, pain which
would have been very acute for ourselves.

A family from the south, says the same author, who was
acquainted with the persons, came to Paris some time ago.
Several of the children were born in Paris ; but those born
there, as well as those brought there from the south, were in
childhood extremely sensitive to cold. One of the daughters
married a man from the north, who is insensible to cold,
provided it is not excessive. The child born of this union
is more sensitive to cold than even its mother ; like her, he
shivers at the slightest fall of temperature, and so soon as
the air becomes cold, he is afraid of leaving the house.
The insurmountable repulsion which some persons have for
touching certain objects : as silk, velvet, mother-of-pearl,
cork, peaches, etc., is well-known, and cases might easily be

215

cited showing how these repulsions are frequently, if not
generally, hereditary. Although, therefore, the sense of
touch concerns physiology rather than pathology, there can
be no question that in the one as in the other, heredity
governs all the phenomena.

The senses of taste and smell are so allied as to be
almost inseparable. Like the sense of touch, these latter
ones concern also physiology rather than pathology, but
where the phenomena are permanently involved in patho-
logical conditions, then heredity is the rule, as in those
which are purely physiological. The specific, as well as the
individual varieties of taste and smell, are alike transmissible.
I have elsewhere referred to the physiological phenomena,
which are undoubtedly hereditary ; but, for obvious reasons,
beyond the fact that every form and variety of the sensorial
development of smell and taste, whether congenital absence,
anaesthesia or hyperaesthesia, in every degree, are subject to
heredity, I cannot go. Purely pathological conditions of
the senses of smell and taste are so generally, merely of a
temporary character, that they cannot be regarded as trans-
missible, but in everything appertaining to the development
and degree of the senses themselves, heredity is distinctly
apparent, as indeed it would inevitably be pathologically, if
their functions required the exercise of special local organs,
as in the case of sight and hearing ; or if, in like manner,
they were subject to characteristic and definite diseases.

From the foregoing observations it will be seen that in
relation to the sensorial qualities, heredity plays its part,
and exercises its influence, not only physiologically but
pathologically also. With regard to sight and hearing, we
have seen that not only the visual and acoustic abnormalities
and diseases are transmissible, but that, in the case of touch,

216

smell, and taste, every degree of development, whether
anaesthetic or hypersesthetic, is alike transmissible, and that
wherever these latter abnormalities become developed to a
morbid degree, here also heredity is the rule. In a word
the sensorial organs, their functions and their diseases, are
alike subject to the law of heredity.

Diseases of the Skin. — Anatomically and physiologically
there can be no question as to the heritability of certain
peculiarities of skin, some of which are, more or less,
predisposed to certain morbid dermatological conditions.
Some of the recorded cases of physiological and anatomical
abnormalities of the skin are very interesting, and all the
more so from the fact of their having been transmitted through
many generations. The well-known case of the Lambert
family is peculiarly interesting, as affording indisputable
evidence of the transmissibility of an abnormal condition of
the skin, which descended through at least five generations.
The peculiar affection from which the family suffered
consisted in their skin being covered with indurated, horn-
like excrescences, affecting the entire body, except the head,
soles of the feet, and palms of the hands. Edward Lambert,
one of the earliest, if not the first member of the family so
affected, had six children, only one of whom ultimately
survived ; but each of them had manifested the same
peculiarity when six weeks old. The surviving son married,
and all his male offspring were similarly affected, this
extraordinary cutaneous condition having descended through
at least five generations. Corns, and the indurated brawny
cuticle of the feet in those who walk bare:footed, present a
somewhat analogous condition of skin.

Another striking instance of the transmissibility of
abnormal physiological phenomena is presented by the case

of Andrian Jeftichjew and his son Fedor, who were exhibited
on the Continent and in England a few years ago, and whom
I had an opportunity of examining during their stay in
London. In Paris they were called Us hommes chiens^ and
in London, the dog-men, Andrian's face being so covered
with hair as to present a striking resemblance to the face of
a Skye terrier. His excessive capillary development is not
true hair, but simply an abnormal growth of the down or
fine hairs which usually cover nearly the entire surface of
the human body. Strictly speaking he has neither head-hair,
beard, moustache, eye-brows, nor eye-lashes, their place
being taken by this singular growth of long silky down. In
colour this is of a dirty yellow : it is about three inches in
length, all over the face, and feels like the hair of a New-
foundland dog. The very eye-lids are covered with this
long hair, while flowing locks come out of his nostrils and
ears. On his body are isolated patches, strewed, but not
thickly, with hairs one and a half to two inches long. The
son, Fedor, who was exhibited in company with Andrian,
was illegitimate, and about three years of age. Andrian's
legitimate children, a son and a daughter, both died young ;
nothing is known of the former, but the daughter resembled
the father. The growth of down on Fedor's face is not so
heavy as to conceal his features, but there is no doubt that
when the child comes to maturity, he will be at least as
hirsute as his parent. The hairs are as white and as soft as
the fur of the Angora cat, and are longer at the outer angles
of the eyes. There is a thick tuft between the eyes, and
the nose is well covered. The moustache joins the
whiskers on each side, after the English fashion, and this
circumstance gives to accurate pictures of the child a
ludicrous resemblance to a well-fed Englishman about fifty !

2l8

As in the father's case, the inside of Fedor's nostrils and
ears has a thick crop of hair. Both father and son are
almost toothless, Andrian having only five teeth, one in the
upper jaw, and four in the lower, while the child has only
four teeth, all in the lower jaw. In both cases the four
lower teeth are all incisors. To the right of Andrian's one
upper tooth there still remains the mark of another, which
has disappeared. That beyond these six teeth the man
never had any others, is evident to anyone who feels the
gums with the fingers. The deficiency of teeth, accompanied
as it is by what is in reality a deficiency, not a redundancy
of hair, accords well with Darwin's view that a constant
correlation exists between hair and teeth. He mentions
as an illustration the deficiency of teeth in hairless dogs.
The tusks of the boar, again, are greatly reduced under
domestication, and the reduction is accompanied by a
corresponding diminution of the bristles. He mentions
also the case of Julia Pastrana, a Spanish dancer or opera
singer, who had a thick masculine beard and a hairy forehead,
while her teeth were so redundant that her mouth projected,
and her face had a gorilla-like appearance. It should rather
be said that in general those creatures which present an
abnormal development in the covering of their skin, whether
in the way of redundancy or deficiency, present generally,
perhaps always, an abnormal dental development, as we see
in sloths and armadilloes on the one hand, which have the
front teeth deficient, and in some branches of the whale
family, on the other, in which the teeth are redundant, either
in number or in size.

To the foregoing cases many more might be added showing
the undoubted heritability of cutaneous physiological abnor-
malities ; but I would now go further, and assert that the

2I9

differentiation of individuals from one another, in conse-
quence of heredity and variability, includes differences in
the structure, functions, quality, and complexion of the skin,
which are not only more or less hereditary, but which, how-
ever normal they may appear, will more or less predispose
the skin to disease. These family and individual normal
differences in the structure, functions, quality, and complexion
of the skin are everywhere known and recognised, so that
I need not here allude to them in any detail further than to
state that, caterts paribus, many of them predispose their
possessors to certain morbid dermatological conditions.

It is well to remember at the outset that " there is nothing
essentially special in the details of cutaneous pathological
changes as compared with those which may occur in other
parts."1 In other words, between the facts of general and
skin pathology there has recently been demonstrated such a
general similarity that the same appearance, changes, and
causes in morbid action are recognised in the diseases of the
integument, as in the pathological conditions of other parts
of the body. It is also necessary that the part played by
various concomitant conditions in each individual should be
estimated and appreciated, as these undoubtedly modify the
character and derivation of the particular disease that may
be present.

Without attempting to give any detailed classification of
skin diseases — infinite in their variety of forms, as multitu-
dinous in the names given to them — I may be permitted to
roughly formulate them in the following ten groups, as given
by Dr. Tilbury Fox — viz., the eruptions of the acute specific
diseases ; local inflammations ; diathetic diseases ; hyper-
and atrophic disease ; new formations ; hsemorrhagic,

1 Dr. Tilbury Fox.

220

neurotic, and pigmentary diseases ; and disorders of the
hair and glands and their appendages. With the exception
of the first — viz., the eruptions of the acute specific diseases
— which I have already discussed — and, perhaps, some of
the parasitic diseases of the hair, there is not one of these
forms which does not come, more or less, under the influence
of heredity. With regard to these two exceptions, heredity,
as I have elsewhere stated, shows its potency, as in the whole
range of organic life, for it develops, sustains, and perpetu-
ates the specific characters of the germs in the one, as it
develops, sustains, and perpetuates the specific characters of
the parasites in the other. How else could they be handed
down unaltered in their specific characters, from generation
to generation, except in accordance with the all-pervading
universal law, roughly estimated by Lamarck — viz., " Like
begets like "; and " Each after his kind," as the Mosaic
record has it ? As I have said repeatedly before, there is
no escaping the law of heredity, for it is as necessary for our
development and perpetuation as the act of generation, or
the air we breathe !

The causes of skin diseases may be thus stated :

(a) Internal, or those which act from within the system
upon the skin.

(b) An innate disposition in the skin tissues themselves to
take on a diseased action.

(c) External, or those which act from without the system
upon the skin. (Fox.)

I am here only concerned with the two former, in which
many of the causes are hereditary ; but as similar diseases
may arise from a combination of both of these causes, it
may be expedient to consider them together, or rather to
consider these morbid conditions of the skin in the causation

221

of which both these sets of factors are implicated. It
may, indeed, be said that the majority of skin diseases are
dependent upon both for their causation, as we may see in
cases of erythema in a rheumatic subject, in connection with
dyspepsia ; eczema in a gouty subject, dependent upon mal-
assimilation ; psoriasis in a scrofulous subject, dependent
upon alteration of the normal healthy character of the
blood ; pruritis in connection with gout, hepatic derange-
ment, or diabetes. Here, for example, in cases of erythema
in a rheumatic subject, in connection with dyspepsia, the
dyspepsia is an internal cause, dependent more or less upon
the rheumatic diathesis ; mal-assimilation an internal cause,
dependent upon the gouty diathesis ; alteration of the normal
condition of the blood dependent upon the scrofulous
diathesis, and so on ; the first producing erythema, the second
eczema, and the third psoriasis : and in this connection it
may be well to emphasise the axiom that the true cause of
the state of any given disease is made up of a number of
phenomena or agencies in combined operation. Excluding
such non-hereditary agents as the acute specific poisons,
medicinal substances, deleterious articles of food, etc., which
may produce skin disease, we still have amongst the internal
causes those more or less depending upon heredity, including
gout, rheumatism, syphilis, leprosy, certain conditions in
which injurious substances enter the current of blood, or
are retained in it in undue proportions, as dyspepsia, mal-
assimilation, functional uterine disturbance, and various
morbid conditions of the liver, kidneys, and intestines ; also
certain conditions of the nervous system, producing hyper-
semia and urticaria, herpes, pemphigus, anaesthetic leprosy,
and that impaired functional power involving loss of control
over the skin nutrition, allowing morbid action of all kinds
to take place more readily.

222

Concerning the innate disposition in the skin tissues
themselves to take on a diseased condition, it is pretty
certain, as Dr. Tilbury Fox observes, that many diseases of
the skin must originate in a disordered behaviour of the
tissues themselves, and do not necessarily depend for their
cause upon any general defect of nutrition. For instance,
cancer is a case in point ; and so also warty growths of all
kinds, fibroma, keloid, and perhaps lupus, are other illustra-
tions of the same thing. In some cases there is just an
excess of growth, a plus state of the nutrition of the tissue,
and nothing more (hypertrophic) ; or it may be a minus
condition (atrophic). In other instances it is a perverted
nutrition, a deviation in the type of the tissue, as in cutaneous
cancer. The epithelial layers may be mainly affected, as
in warts, corns, xeroderma, and ichthyosis, or the connective
tissues of the skin may be specially involved, as in keloid,
fibroma, morphoea, and scleroderma. Moreover, all the
diseases of the sweat glands and follicles — of the sebaceous
glands — of the hair and hair follicles, and of many of
those of the nails, belong to the same category, and are all
subject to the influence of heredity.

As showing how predisposition and insusceptibility — both
of which I have elsewhere proved to be more or less the
result of heredity — may influence parasitic diseases of the
skin, I may here quote from Dr. Alder Smith, who says : —
" All children are not equally susceptible to ringworm. A
certain unknown condition of the skin is necessary for the
growth of the fungus. Some children never take ringworm,
though certainly liable to become infected ... On some
the fungus takes but slight hold, and is easily destroyed ;
others again appear to be extremely susceptible . . . The
difference in these cases must depend on some peculiar

223

nutritive condition of the soil or material in which the
fungus develops, or upon some special state of the general
health or constitution. In fact, the state of the soil is a most
important condition, and the rapidity with which a small
spot of ringworm will spread before it comes under efficient
treatment, depends chiefly upon the peculiar and unknown
condition of the soil or nidus." In seeking to account for
this " unknown condition," whether of the nature of pre-
disposition or insusceptibility, I maintain that it depends
upon idiosyncratic peculiarity in the structure of the infected
parts, which, like all other idiosyncratic conditions, has
been transmitted hereditarily. Having already discussed the
idiosyncrasies of structure represented by certain inherited
proclivities of tissue, I need not refer to them here in any
detail further than to state that they account for those pre-
dispositions and insusceptibilities referred to above by Dr.
Alder Smith, and are very frequently the primary causes of
:such skin diseases as icthyosis, psoriasis, xanthelasma,
molluscum fibrosum, etc., and probably also of " steatomata
of the scalp, lipomata, adenomatous tumours in the breast,
multiple uterine fibroids, milium, whether on the face or
elsewhere, and a host of others." l

As illustrating further, and more forcibly, the inherited
proclivities of the integument I may here refer to the
various forms of acne, which undoubtedly denote original
and heritable peculiarity in the structure of the skin. As
Mr. Hutchinson says : — " The location of acne on the face
is probably often explained by pre-existing peculiarities in
the state of the skin of the face . . . Acne is very constantly
hereditary, the same form often prevailing in several members
of a family, and acne tuberosa, I believe, often descends

1 Hutchinson.

224

in several generations from father to son." The differences
in the various forms of acne are accounted for primarily by
differences in the skin of the affected individuals, and these
differences may be said to consist in relative thickness of
the skin, and a hyper-development of the sebaceous system,
which are unquestionably subject to heredity.

Eczema is another affection dependent more or less upon
a constitutional proclivity, which is also hereditary. Usually
associated with gout, scrofula, or neurasthenia, eczema may
result from either of these conditions, all of which are
hereditary, and it may be safely asserted that those individuals
who have inherited the gouty, scrofulous, or neuropathic
diathesis are especially predisposed to eczematous affections.
Eczema must be regarded as practically the most important
of cutaneous diseases, if only on account of its comparative
frequency, including as it does more than one-third of all
cases of those diseases which come under treatment. It is
also remarkably protean in its manifestations, showing itself
under the most varied forms. The predisposition to eczema
differs to a remarkable extent in different individuals. As
with some persons every trifling irritation of the stomach
gives rise to gastric catarrh, so in others a mere chafing of
the skin will cause an attack of eczema. Amongst the
predisposing conditions to this affection may be mentioned
chlorosis, rachitis, scrofulosis, gout, albuminuria, diabetes,
dyspepsia, gastric and intestinal catarrhs, dysmenorrhoea,.
uterine affections, lactation, and pregnancy. Psychical
influences may also be the immediate cause of the complaint
where a predisposition exists. Persons having a very
delicate skin are more liable to eczema, and susceptibility in.
this direction is also increased by repeated attacks. That
eczema is in itself hereditary, beyond a mere predisposition.

225

to it, is also beyond doubt, as several authors have met with
frequent instances of its occurrence by descent. That so
few have recorded such cases is probably due to the fact
that in private practice only the most inveterate cases come
under notice, in which category hereditary eczema must
undoubtedly be placed. For example, a girl of sixteen was
placed under the care of Drs. Veiel (pere et fils) by her
father, a medical man. He himself, and his mother, as also
his second daughter, were sufferers from the complaint.
Similar examples might be multiplied. Eczema is observed
with special frequency in scrofulous and phthisical families.1
Psoriasis is another well-known skin affection in which
heredity, if not its sole cause, plays a very prominent part,
and illustrates many of its peculiarities, as atavism, etc. No
rigid proof, says Weyl, can be brought at present that psori-
asis develops de novo> or can be produced mechanically or
chemically. Bazin regards it as a constitutional diathesis,
mainly hereditary, which is either of arthritic or herpetic
origin, and gives, as he imagines, the characteristic dif-
ferences of both forms. Others assume principally a single,
unknown, internal cause — the dartrous diathesis. Weyl,
further, considers it probable that it is due to a functional
weakness of the nervous centre regulating the nutrition of
the skin, dependent on hereditary taint; this view is favoured
by the constant monotonous form of the efflorescence, and
its tendency to symmetrical development. The anatomical
process is merely the peripheral projection of the functional
central disturbance. According to Neumann, prurigo and
ichthyosis have never been found associated with psoriasis,
showing that all dermatoses may be combined, and that a
number of them exclude one another.3 There can be no

1 Dr. Th. Veiel (Ziemssen). 2 Dr. Weyl (Zeimssen).

226

doubt that psoriasis not uncommonly occurs in several
members of a family, and that it may be transmitted for
several generations. Dr. McCall Anderson's view as to the
cause of this affection is that it is an inherited perverted
tendency of tissue formation, which tendency lies dormant
until called into activity by some exciting cause ; and it is
probably not due to a special blood condition, or dyscrasia,
or diathesis, but is due to a peculiar morbid tendency of
parts of the skin, which is obviously hereditary. In other
words, it is neither primarily nor altogether due to any
condition of the blood or nervous system, but its causation
materially consists in an inherited proclivity of cutaneous
tissue — an idiosyncrasy in the structure of the skin itself.
Mr. Hutchinson explains the entire absence of psoriasis in
infancy and early childhood by suggesting that when the
structural idiosyncrasy is very strong, it may manifest itself
in a different form. Thus, he thinks it not improbable that
the ichthyosis of infants may be in this way the representative
of the psoriasis tendency in its intensest form. Psoriasis is,
therefore, markedly hereditary, persisting through many
generations, and will sometimes be found to undergo
apparent transmutation with other forms of skin disease, as
nummular eczema, lichen ruber, and pemphigus.

Of all other skin diseases, none affords such direct proof
of its hereditary character as ichthyosis, which generally
occurs in several members of the same family, but frequently
omits a generation, or fails to descend in the direct line.
Hardy goes even so far as to assert that if other members of
the family are not found affected with ichthyosis, this disease
will certainly be found affecting some near friend of the
patient's. There are many instances on record where the
disease was transmitted from mother to son, and from father

227

to daughter, although usually transmitted to those of like
sex. Its frequent occurrence in brothers and sisters, without
any external influences being recognised, is further proof of
the hereditary nature of ichthyosis.1

Of the other skin diseases — and their name is legion — I
maintain that there is scarcely one of them — not one of
them, in fact, of a constitutional character— which is not
more or less subject to the law of heredity, either as an
actual or predisposing cause. To discuss those forms which
I have left unnoticed in any detail would occupy more space
than I can at present command, and would, after all, be a
work of supererogation, as the various forms already referred
to are not only in themselves the most important among the
dermatoses, but may be said to fairly represent the various
classes of cutaneous affections. Whether, therefore, of the
nature of local inflammation, diathetic diseases, hyper- or
atrophic disease, new formations, haemorrhagic, neurotic, or
pigmentary diseases, or disorders of the hair, glands, and
their appendages — heredity is a potent factor in their pro-
duction, either by actual transmission, or a predisposition
resulting from inherited morbid proclivity in the tissue of
the skin itself.

I have already said that the details of cutaneous patho-
logical changes manifest nothing essentially special, as
compared with those occurring in other parts of the body ;
and thus, in the local inflammations of the skin — whether
erythematous, catarrhal, plastic, or suppurative — we find the
inflammatory process identical with that in other parts, and
in this connection it should be remembered that the more
frequently the tissues have yielded to any special process of

1 Dr. E. Lesser.

228

inflammation, the more prone they are to yield again ;x and
thus, a diathetic condition may be established in an indi-
vidual, who may transmit the same to his offspring. It is,
at any rate, a well-known fact that while some individuals
and families are especially predisposed to inflammatory
processes, others are not, and it is amongst the former that
local cutaneous inflammations generally occur. With regard
to the cutaneous eruptions which are known to be local
manifestations of diathetic states, and which include scrofu-
loderma, syphiloderma, leprous eruptions, frambcesia or
yaws, etc., it goes without saying that heredity is a potent
underlying element in their production.

In those affections of the skin included under the names
hypertrophic or atrophic there is essentially an innate dis-
position in the skin tissues themselves to take on a diseased
condition, and the same may be said of the majority of the
diseases of the sweat and sebaceous glands, of the hair,
follicles, and nails. In the former category are included,
amongst the hypertrophic variety, warts, corns, xeroderma,
ichthyosis, keloid, fibroma, morphoea, and scleroderma : and
amongst the atrophic, senile and linear atrophy, and general
marasmus. As these are all more or less dependent upon
an inherited predisposition in the integument itself, it is
evident that here, too, heredity is of prime importance in
their production.

Concerning new formations, I have elsewhere shown that
they depend upon diathesis, constituting as they do one of
the diathetic varieties. This group includes lupus, cancer,
rodent ulcer, and xanthelasma. Mr. Hutchinson regards

1 For a detailed discussion of this interesting subject the reader is
referred to Mr. Jonathan Hutchinson's most admirable and very
suggestive work, " The Pedigree of Disease," to which the writer is
under many obligations.

229

the former as "a sort of cross produced by tendencies at
once to scrofula and cancer, and that it receives many
modifications from peculiarities in the patient's skin, and
his morbid tendencies in one or the other direction." Much
the same may be said with regard to rodent ulcer, and as to
cancer I must refer the reader to what has already been said
as to the diathesis of malignant new growths. Xanthelasma
is " in part a new growth, and in part a fatty degeneration,"
depending upon long hereditary descent, and may be
regarded as the original offspring of the hepatic diathesis.

Of the hsemorrhagic division of skin diseases purpura is
the only illustration, and it is said to be non-hereditary ; if
so, it must be regarded as the exception which proves the
rule ! Although it has been asserted that this condition
depends upon a morbid alteration in the liquor sanguinis,
and that it also involves an affection of the vaso-motor
nervous system, as a matter-of-fact nothing definite is known
as to its etiology. As to its being the result of a diseased
condition of the vascular system, which has also been
stated, although evidence of any anatomical alteration in
its structure is wanting, " yet there are certain conditions in
which a disease of that structure must be presupposed,
which exist whenever slight causes give rise to haemorrhages
in parts far distant from each other, and which constitute
what is known as the hamorrhagic diathesis" l I have
elsewhere shown that, according to Mr. Jonathan Hutchinson
and others, this diathesis is the result of the long descent of
gout; and why, may I ask, should not purpura be the
result of the complicated agencies of heredity acting and
reacting on human tissues, amid various morbid conditions
for an indefinite period, until it is produced in certain

1 Professor Ernst Schwimmer.

23°

individuals ? If all our tissues, whether in health or disease,
are subject to heredity, I do not see why this comparatively
rare condition — whether dependent upon vascular or vaso-
motor change, should not occasionally be evolved in the
case of certain individuals, as the result of complicated
tissue proclivities which have been inherited. Until,
however, the exact pathological conditions which engender
purpura are thoroughly established, I am content to allow
this affection to remain amongst the category of those whose
dependence upon heredity is "not proven." It should
not, moreover, be forgotten that a purpuric condition is
also associated with scurvy, and that this latter affection
is included amongst the diet-diatheses by Mr. Jonathan
Hutchinson.

Amongst the neurotic affections of the skin are included
hypersesthesia, anaesthesia, and pruritus. The two first are
so evidently dependent upon neurasthenic or neuropathic
conditions, which are admittedly hereditary, that they need
only be mentioned ; and the latter can only be included
amongst those cases of idiosyncratic susceptibility in which
the skin is inherently hypersensitive, as manifested by the
different results produced upon different individuals by the
bites of various insects, contact with woollen clothing, etc.
Of those cutaneous affections depending primarily on
deposit or alteration of pigment, and including melasma
and leucoderma, nothing much can be said, as nothing
definite is known as to their causation. They are, however,
of little importance, and what I have said as to purpura will
apply equally to them. It may, however, be remarked that
certain individuals and families are more subject than others
to the forms of pigmentation resulting from exposure to the
sun, and that chloasma gravidarum characterises many
families during the pregnant state.

231

Instead of considering the multitudinous forms or
varieties of skin affections in detail, I have preferred, for
obvious reasons, to deal with them for the most part
synthetically, and have now referred to the various groups
into which every case of skin disease must fall. I have
subjected each group to an examination as to how far
heredity can be regarded as an element in its production,
and I think I have shown that, in at least the majority
of them, hereditary transmission or predisposition is an
etiological factor of essential importance.

My observations on the all-pervading law of heredity must
now draw to a close. I can only hope that the results of
my study may be as gratifying to my readers as the task
has been to myself, and that at least some good may have
been affected in consequence of my inquiry. I have, for I
believe the first time, subjected the various diseases and
disorders to which the human body is liable to an
examination, as to how far they are the results of or
referable to hereditary transmission, and in the words of
Mr. Jonathan Hutchinson, to whose labours I owe so much,
"It is abundantly sufficient for my ambition, if, availing
myself thankfully so far as my knowledge extended, of the
labours of those who have gone before me, I have succeeded
in any degree in making opinion more definite, and giving
emphasis to that which is true."

In conclusion, the following summary of the views
enunciated in these papers may not be altogether unac-
ceptable.

Summary. — Heredity, as we have seen, is one of the
fundamental laws of living Nature, by which all organic
beings tend to repeat themselves in their progeny, and it
underlies the grand evolutionary processes by which,
according to the Darwinian theory, all organic beings have

232

been produced. The effects of this great law have been
recognised and appreciated from the earliest ages ; and,
while the axiom of Lamarck that " like produces like " may
be true as a generalization, yet the tendency to variation
which is manifested in all animals as resulting in the
differentiation of individuals — is so potent as to frustrate
the attainment of the ideal law.

The office of Science consists in the interpretation of
natural laws, by means of the study of phenomena in rela-
tion with experience. Heredity is a physiological necessity
of our being inseparably connected with reproduction, and
the mysterious source of both may be traced to the fusion
of the sperm and germ cells, resulting in a germinal vesicle.
Analysing the human organism somewhat in detail, it is
found that the likeness between parents and children,
although by no means absolute, characterises not only every
element of their form, features, and expression, but also
every action, every function of their physical being, exten-
ding even to the transmission of idiosyncrasies, habits, and
acquired modifications, so that every anatomical conforma-
tion— every physiological function and process — the varieties,
and the minutest peculiarities of the individual in structure,
composition, and properties, are alike found to be subject to
the grand law of heredity.

The correlation and interdependence of the laws of
heredity and variability are well recognised in the great
evolutional theory of Darwin; and the so-called laws of
heredity, under which all the main facts are usually grouped,
may be thus briefly formulated : —

(1) Direct Heredity.

(2) Reversional Heredity or Atavism.

(3) Collateral or Indirect Heredity.

(4) The Heredity of Influence.

(5) Specialised or Initial Heredity.

233

Between physiology and psychology there exists not only
an intimate correlation but an exact parallelism. The Brain
is the organ of the Mind, and thought but the result of
brain action ; and as the brain, as regards its size, structure,
and qualities is hereditarily transmissible, we are warranted
in asserting that every mental or intellectual state is
conditioned by a pre-existing physiological state and that
psychological heredity has its source in physiological here-
dity. Like all other groups of natural laws, physiology and
psychology are simply terms used to denote the groupings
of certain phenomena which experience has enabled us to
perceive are reducible to law. The physiological phenomena
concern unconsciousness, but inasmuch as every mental con-
dition implies and necessitates an antecedent physical
condition, there is of necessity an intimate correlation
between both. Thus the functions of the spinal cord, the
medulla oblongata, the cerebellum, are performed uncon-
sciously, and even the brain itself is capable of unconscious
cerebration.

Proceeding from the unconscious towards the conscious,
we find that instincts, owing to the fact that the psychical as
well as the physical nature are unquestionab'y transmitted
from parents to their children, are hereditarily t ransmissible ;
so also are the modes of sensorial activity denominated the
perceptive faculties ; as every deficiency, and extraordinary
development of any of the senses are indubitably passed
on from parents to their offspring. To these latter must,
moreover, be added memory and imagination, which are
likewise potentially transmissible by heredity. Are the
higher, like the lower modes of intellect, transmissible ? As
the unity of the intellect is recognised and admitted by all
schools of thought, and as facts undoubtedly prove the

234

heredity of the lower intellectual modes, it must follow as a
natural sequence that all the higher forms of the human
intellect are also subject to this law. If we regard intellect
and reason from a transcendental point of view, they tran-
scend experience, and are thus beyond the sphere of science ;
but if we consider them phenomenally, there is no reason
why they should be exempted from the law of heredity, and
thus considered, they are without doubt inherited.

In like manner the sentiments and passions are also
transmissible; and if we avoid all polemical discussion
as to free-will and heredity, the human will, regarded
phenomenally — that is with regard to the immense resolu-
tion, boldness, courage, self-confidence, and mastery over
the timid and irresolute which characterise the possessors of
strong wills — is also unquestionably hereditary ; so too the
evolution and fixation of national characteristics are primarily
the result of heredity. From this rapid and imperfect
summary it will be seen that all that we have and are as
individuals constituted for the performance of certain
functions, we owe to heredity, with the exception of the
developing influences of our " environment " through life,
and the educational processes to which we have been
subjected.

Having thus far proved the inheritance of man's physio-
logical and psychological nature in detail, I discussed the
individuality of man as developed by the interaction of
heredity and variability, and showed that however perfect
the likeness transmitted from parents to their offspring, it is
never either organically or dynamically exact ; and however
closely the partus may resemble the parens, physically,
mentally, or morally — however closely the former may
resemble the latter with regard to temperament, idiosyncrasy,

235

diathesis, and hereditary predisposition — yet each child
preserves its own individuality by reason of the differentiation
produced by natural variability, to which every organic being
is subjected, in addition to heredity. Remembering that
each one of us has inherited certain peculiarities — physio-
logical, psychological and pathological — which we, in turn,
shall pass on to our descendants, I thus sought to prove the
reason why every individual differs in these respects from
every other, and why those peculiarities which distinguish
us from one another in health should also tend to modify or
intensify our relative proneness to certain morbid affections,
by the neutralisation or development of the morbid suscep-
tibilities or predispositions which have been transmitted to us.
Defining diseases, in the abstract, as not entities, but mere
groups of modifications of structures already in existence,
and of actions always progressing in a vital system — in fact
particular conditions of the living body, new phases of its
vital manifestations, whether of the nature of functional
derangement or organic or textural degeneracy — I was led
to conclude that the differentiation of individuals concerns
not only their physical nature and functions, their mental
qualities and moral character, but also their morbid
processes, whether functional or organic. In other words,
as the physiological and psychological nature of every
individual — inherited and acquired — differs from that of every
other, so too must every individual differ from every other as
to his pathological predispositions. Thus, whether we con-
sider man physiologically, psychologically, or pathologically,
we find the potency of heredity in his every aspect, and so
far as this influence extends there is an exact parallelism
between physiology, psychology, and pathology; they are,
in fact, names denoting man's organism and dynamism in

236

health and disease, both of which I contend, in diseases as
in health, are essentially subject to the law of heredity.

In considering what is meant by predisposition, I dis-
cussed it under the following heads — viz., hereditary, aetal,
sexual, and acquired, and showed that it consisted in a
peculiar state of the physical and mental constitution of
every individual, mainly hereditary, which renders him
specially liable to suffer injuriously from the effects of cer-
tain morbific agents, and when these latter are of a non-
specific type, predisposition will determine the particular
disease which it shall induce in each of several individuals
similarly exposed to it : whilst in the case of a specific agent
or morbid poison, it determines the relative liability of
several individuals similarly exposed to it, to become the
subject of the particular diseases it is capable of originating,
and also influences the severity of its attack.1 In other
words, just as every individual differs from every other
physiologically and psychologically, so he differs from every
other in his predisposition to disease, and all these differ-
ences are the result of heredity and variability. Predis-
positon is, in fact, a tendency, mainly hereditary, in the
tissues or organs of the body to readily assume certain
morbid processes, in the presence of certain exciting causes,
and may thus be regarded as the result of a minor degree
of heredity to that in which certain morbid conditions are
actually transmitted. There is probably no individual in
existence who has not inherited some predispositions to
disease, and we thus see that heredity and variability
influence man physiologically, pyschologically, and patho-
logically, in fact, as in health, so also in disease. Instead of
a predisposition, it may be an insusceptibility to certain
1 Dr. W. B. Carpenter.

237

diseases which is inherited, but this latter can only be
regarded as an effect of the same causes working differently,
as they do in every individual — producing in one a predis-
position, in another an insusceptibility. Regarding, then,
hereditary predisposition to disease as a scientific fact, and
bearing in mind that none of us are free from its influence
— since it is also scientifically correct to say that every atom
and function of man's physical and mental nature are also
subject to heredity — it assuredly must follow that the same
atoms and functions are liable to certain morbid processes
in consequence of the same influence, especially as diseases
are merely particular conditions of the living body, new
phases of its vital manifestations, whether of the nature of
functional derangements, or of organic or textural degeneracy.
To sum up : man, physiologically and psychologically, to
the minutest detail, being subject to the law of heredity, it
must follow that he has also inherited certain predispositions
to disease which, in the presence of certain exciting causes,
will develop into active morbid processes : in a word, man
is alike subject to heredity in health and in disease.

In addition to hereditary predisposition, we find that the
individuality of man consists also of temperament, idiosyn-
crasy, and diathesis. How do these latter affect the pre-
dispositions to disease in individuals ? The temperaments are
the sanguine, nervous, lymphatic, and bilious. The sanguine
predisposes to diseases characterised by the rapidity of the
inflammatory process, and predisposes its possessors to
acute affections, which develop themselves regularly and
completely, defervesce rapidly, and generally with well-
marked symptoms of crisis. The nervous temperament
predisposes to disorders of the nervous system, convulsive
diseases, various congestions and haemorrhages, hepatic and

238

internal obstructions, neuralgia, insanity, and melancholia.
The diseases to which the lymphatic temperament pre-
disposes are generally of a chronic character, and of an
asthenic type, as debility, tuberculosis, scrofula, and dropsy;
and the bilious temperament tends to dyspeptic affections,
hypochondriasis, and hepatic derangements generally. The
temperaments are types of inherited physical and mental
constitution, and are generally "mixed" in different in-
dividuals, while one may predominate. That they predispose
to disease we have just seen. Idiosyncrasies, always
inherited, also predispose to disease, or may produce
insusceptibility. There can be no doubt that they depend
upon peculiarities of physical structure. They predispose
to certain morbid processes, as, for example, the specific or
exanthematous fevers. It may be an extraordinary immunity
that they reveal, or an incredible degree of susceptibility,
and they account for the various degrees in which different
individuals are affected by scarlet fever, small-pox, typhus
and typhoid fever, diphtheria, erysipelas, syphilis, carbuncle,
etc. " There are few of us without our idiosyncrasies, and
their variety is innumerable."1

The diatheses are of still greater importance, consisting as
they do of morbid proclivities existing in an individual or
family, in consequence of his or their heredity and environ-
ment ; or, still better, " of any condition of prolonged
peculiarity of health giving proclivity to definite forms of
disease."2 I adopted the classification of Mr. Jonathan
Hutchinson because it is founded on a scientific basis, and
is in accord with the natural history of disease, and con-
sidered in detail the following varieties : — The three universal
diatheses, viz. : the scrofulous or tubercular, the rheumatic,
1 Mr. Jonathan Hutchinson. 2 Ibid

239

.and the catarrhal. The two climatic, viz. : the malarial, and
the bronchocele. The four dietetic, viz. : the gouty and
hsemorrhagic, the leprous, the scorbutic, and the rachitic;
.and, after these the diathesis of malignant new growths, the
diathesis of senile degeneration, the visceral diathesis, etc.
It would be very easy to add to these in every direction, but
those referred to suffice to show that my object has been to
include diathetic diseases in such groups as bear upon their
long descent by heredity, and not the elaboration of a mere
detailed classification, which I could have readily supplied
by exercising a little ingenuity. Without recapitulating the
details of the various diatheses considered, I shall now
content myself by repeating that, as the so-called Laws of
Nature represent merely the grouping of certain phenomena,
so diathesis may be regarded as the grouping of certain
constitutional peculiarities, having certain pathological ten-
dencies, in certain families or individuals ; and as every
individual differs from every other, in every respect, we must
naturally be prepared to admit a similar differentiation with
regard to his diathetic peculiarities. Diatheses are, in fact,
but rough types of constitutional peculiarities, showing a
predisposition to certain diseases, which may be variously
blended in different individuals, while the original type is
more or less preserved.

It should, however, be remembered that the temperaments,
idiosyncrasies, and diatheses, however influential as factors
in modifying morbid processes in individuals, receive their
force and character from heredity, and may thus be said to
be merely effects of hereditary predisposition specialised in
certain sets of individuals; but hereditary predisposition
means far more than the temperaments, idiosyncrasies, and
•diatheses, for it not only includes all these, but also implies

240

that a morbid predisposition which has arisen in some
individual, whether ancestral or parental, has, by heredity,
been transmitted to his offspring, and either intensified by
descent, or modified by age, sex, or accessory circumstances.
In speaking of diseases as hereditary, I do not mean that
the diseases themselves, occurring either in ancestors or
parents, are actually transmitted to their offspring (who,
under those circumstances, would be born with them), but
what is really meant is that a certain organic constitution is
inherited by the children, which being likely to undergo
pathological development in the ordinary circumstances of
life, is therefore described as a constitutional predisposition
or tendency to disease.

If it is admitted, as I have indicated, that every individual
is subject to heredity in his physical, mental, and moral
constitution, and to such an extent in his physical organisa-
tion that the minutest structure of his every organ and tissue
is characterised by it — it seems to me but a natural sequence
that the life-history of his parents' organs and tissues will be
re-enacted to some extent, at least, in his own, and that
when they have developed organic or tissue derangement or
degeneracy of any kind, he, too, will at least have inherited
a predisposition to the same. This, I think, may be accepted
as a broad statement of a general truth — the truthfulness of
which is not assailed even when we consider the effect of
such modifying factors as individual varieties of age, sex,
and circumstances.

With the object of inquiring how far this view is supported
by the records of experience, and of actual disease, I passed
in careful review the majority of the diseases " which flesh
is heir to," including intra-uterine diseases, diseases of the
circulatory and nervous systems, of the respiratory organs,

241

the kidneys, the chylo-poietic system, the liver, chronic and
acute infectious diseases, diseases of nutrition, and of the
locomotive organs, of the special senses, and of the skin,
and the result is now before the reader. If my examination
has served no other good, it has, at least, established in my
own mind the accuracy of the views herein enunciated, and
I can only hope that the mass of facts which I have brought
to bear on the affirmative side of the question may, at least,
serve as an inducement to other observers to take a livelier
interest in the subject. As far as the groups of diseases
which I have considered are concerned, it seems to me that
the facts recorded prove beyond a doubt that children inherit
from their parents not only their physiological and psycho-
logical nature — modified in every case to some extent by
variability — but also a predisposition to the constitutional
diseases or disorders from which they have suffered, and
that, in disease or in health, heredity is a factor of prime
importance.

So far as I am aware a systematic attempt has never
before been made to trace the influence of heredity as an
important factor in the origin and development of the
diseases which afflict humanity, and if the facts which I
have adduced tend to prove that heredity influences them
all, and that because we owe our organic nature — all that we
have and are, with the exception of the influences of our
environment — to this universal law, therefore our morbid
predispositions spring from the same source, I shall be well
satisfied. I have sought to establish a parallelism between
physiology, psychology, and pathology as representing man
in health and disease, and I think I have succeeded in
showing that heredity governs these three aspects of his
organic nature and its condition. Be that as it may, heredity

242

is a fundamental and universal law of living Nature, and'
there can at least be no doubt that the entire physiological
and psychological nature of parents is transmitted, with
some modifications, to their children ; this being so, it
assuredly follows that disorders or diseases, which are nothing
more than modifications of structures already in existence,
and of actions already progressing in a vital system, are
likewise transmitted, and usually in the form of a predis-
position with which the tissues of the children are mysteri-
ously branded. In a word, if the physiological and
psychological nature of man is inherited and transmissible,
so must everything that concerns his pathology, except that
which he owes to the influence of external circumstances
during his " struggle for life."

Before concluding I must allude, however briefly, to
another and equally important aspect of heredity — viz., that
concerning the transmissibility of man's moral nature — and
I approach this subject with considerable diffidence, feeling
that I am about to tread on very delicate ground. At the
very outset of every study of morals we are met by the
mysterious and inextricable problem of free will. I wish it
to be distinctly understood, however, that my remarks are
made in a purely scientific spirit, and entirely apart from
theological dogma or doctrine of any kind. As I have
elsewhere stated, if phenomena be reducible to a law, their
investigation constitutes a science. Science can only deal
with phenomena and experience; and when we come to
regard the ultimate causes of any of these groups of natural
phenomena, and find them not reducible to law, they
transcend experience, and Science pauses paralysed at the
very threshold of such an inquiry. But just as science can
concern herself with the phenomena which are purely physical

243

or mental, so it is in her province to observe and interpret
phenomena which belong to what is called the moral nature
of man, in the light of experience ; and so far as the purposes-
of this work are concerned, we may rest assured that as in
the physical and mental nature of man heredity exercises
a most potent influence, so it does with regard to that
part of his individuality which is denominated moral. In
a word, heredity dominates the whole individuality of man.
In every purely scientific estimate of this individuality the
moral aspect must be regarded from the same standpoint
as the physical or mental, and it is here that Science and
Theology have waged their fiercest battles. Ribot, in
discussing the irreconcilability of heredity and free-will, says :
" Clearly there can be but two hypotheses — either we must
say that at every birth there is an act of special creation,
which places in each being the germ of its character, of its
personality ; or we must admit that this germ is the product
of preceding generations, and that it necessarily comes from
the nature of the parents and from the circumstances of the
generative act" Here I leave this question, having no wish
or intention of discussing it, but I contend that as there is
a parallelism between the physiological and psychological
nature of man, so there is, and must be, between his
psychological and moral nature, and that they are all equally
hereditary.

The moral nature of man has been developed, as his
mental nature has been, by heredity acting through count-
less aeons of time part passu, and coterminously with the
progress of civilisation. In his primitive state of barbarism
and savagery man had no adequate idea of morality. To
hunting succeeded pastoral pursuits, and to pastoral, agri-
cultural, and it is only with the latter that we can associate

244

the dawn of civilisation. " Primitive man, ignorant and
idealess, the slave of his appetites and instincts, which were
simply the forces of nature freely acting in him, rose but
very gradually to the conception of the ideal. Art, poetry,
science, morality, all those highest manifestations of the
human soul, are like some frail and precious plant which has
come late into being, and been enriched by the long toil of
generations."1 Carlyle has said that civilisation is only a
covering underneath which the savage nature of man con-
tinually burns with an infernal fire ; and that the philosopher
was right is easily proved by the facility with which, on
provocation, even the most civilised and highly educated
manifest a reversion to the primitive instincts of the race,
which in a moment may burst all the bonds which civilisa-
tion has imposed upon them — when the brute nature appears
with all its unbridled appetites and savage passions, and
reasserts itself in its primitive barbarism. For, as Ribot has
well said, there exist in the bottom of the soul, buried in
the depths of our being, savage instincts, nomadic tastes,
unconquered and sanguinary appetites, which slumber but
die not. They resemble those rudimentary organs which
have outlived their functions, but which still remain as
witnesses to the slow, progressive evolution of the forms of
life. And these savage instincts, developed in man during
the past, whilst he lived free amid the forests and streams,
are from time to time recalled by heredity, as though to let
us measure with the eye the length of road over which we
have travelled. The basis of morals is responsibility ; but
heredity influences alike tendencies which are resistible and
those which are irresistible, and here we are once again met
with the unceasing conflict between free-will and fate, and I
will only add that in this warfare, fatalism is more often
1 Ribot.

245

triumphant than is usually admitted or imagined. Even
Burdach, a staunch supporter of the free-will theory, admits
that "heredity has actually more power over our mental
constitution and our character than all external influences,
physical or moral." To quote Ribot once more : " If it be
admitted," he says, "that the moral act comprises a great
number of ideas, judgments, and sentiments (as has been
already shown by the influence of heredity on the develop-
ment of sensibility and intelligence), then heredity also exerts
a great influence on the formation of habits and of moral
ideas — moral heredity is only a form of psychical heredity"

To escape, however, from theory to phenomena and
experience which we can deal with in a spirit of scientific
inquiry, properly so-called, and apart from metaphysical
disputations which are too frequently hypothetical, the
reader is referred to the earlier portion of this work, where,
in considering the heredity of the sentiments and passions,
I have alluded to tendencies to vice and crime as a heritage
which descends with the certainty of fate. There is, in
fact, no form of vice or of crime which may not be per-
petuated by heredity, and, if space permitted, it would be
an easy task to cite manifold and indisputable cases to
prove this assertion. I therefore maintain that like the
physical and mental nature of man, his moral nature alsa
is transmitted hereditarily. I have no desire to separate
the resistible from the irresistible tendencies which are
thus transmitted, as this would involve theological argu-
ments which I have neither the intention nor the capacity
to discuss ; but bearing in mind the influence of circum-
stances, in addition to that of heredity, in the development
of character, I may be permitted to ask if our legislature
and our codes of morality have adequately considered these

Q

246

combined influences in their efforts to mitigate the evils of
crime and vice. I trow not. It must be admitted that
there are many individuals to whom Nature and Life seem
to have been so cruel, that they appear to have little or no
chance in the struggle for existence. We have already
seen that cause and effect underlie all moral, as they do all
physical and mental phenomena ; and when we peruse the
life histories of such as these, we cannot but be impressed
by the fact that Nature, by her inexorable law of heredity,
has so handicapped them in the race, and Life has
surrounded them with such baleful circumstances that
success seems all but hopeless and impossible. One of
these poor souls now and again

" Breaks his birth's invidious bar,

And grasps the skirts of happy chance,
And breasts the blows of circumstance,
And grapples with his evil star. "

But alas ! how many go down through suffering and crime
to disease and death, God alone knowing how hard it was
for them to do anything else. Schiller says " this is the
peculiar curse of evil, that it must continually reproduce
evil ; " whilst we therefore glibly prate of " moral responsi-
bility," let us trust that the All-Father may in His infinite
goodness and mercy, judge us with both, and not as we
judge one another. Calderon, in his tragedy " Life a
Dream," puts into the mouth of King Basilius, speaking of
Sigismund, the following words : —

" Though his inward disposition

Has destined him to destruction,

Still he can avoid it ;

Since the most obstinate fate,

The most ungovernable desires,

The most unfavourable stars,

Are able only to direct the will,

But conquer the will they cannot.

247

I cannot, however, but see that, if Nature has laws at all,
they must be universal, and if cause and effect underlie all
her phenomena, then there must be many to whom life has
been but a curse ; and although we must not therefore regard
them as personally irresponsible, yet we must admit that
even the strongest and the best, those whom Nature has
endowed with the greatest power of resisting evil, might
likewise fall and fail, thus handicapped by Nature, and amid
such life surroundings.

I must confess to having no faith in that selfish, stilted
theology which regards all men from the same human
standpoint, ignoring in most the heritage of evil, making
no allowance for the various circumstances of their lives,
and pouring out the vials of their wrath upon the sinner
rather than the sin. We are all differently constituted by
nature, and we have all a different environment in life ;
and whilst remembering ever that "it is human to err,"
we should not forget that what may be a temptation to one
man may be none at all to another, and act towards our
weaker brother accordingly. Whilst admitting that all men
are morally responsible for their actions, it appears to me,
in the light of heredity, and with regard to the differences
of our environment, morally impossible that a God of
infinite love and mercy can judge us all alike as we too
frequently do each other. In the meanwhile, whilst
allowing theologians to settle such disputes amongst them-
selves, I boldly affirm that heredity governs man alike in
his physical, mental, and moral nature, whilst with variability
it develops and maintains his individuality, which differs
from that of every other of his kind.

INDEX.

Acne, Heredity of ... ... ... 223

Acute infectious diseases, Heredity of ... 195

Acute infectious diseases, Classification of 195

Adynamia, Vascular, Diathesis of ... 102

Affections, Skin, Diathesis of ... ... 102

Affections, Phenomena of the ... ... 60

Alcoholism, Hereditary ... ... 138

Alder Smith, Dr., quoted ... ... 222

Amann quoted ... ... ... 132

Amyloid disease of kidneys, Heredity of 156

Amyloid degeneration... ... ... 165

Anaemia, Heredity of ... ... ... 187

Anaemia, Progressive pernicious, Heredity of 189

Anderson, Dr. McCall, quoted... ... 226

Anstie, Dr., quoted ... ... ... 130

Apoplexy, Heredity of ... ... 138

Armstrong, Dr., quoted ... .. 77

Artery, Abnormal distribution of radial,

Hereditary ... ... ... 120

Atavism ... ... ... 27

Automatism, Phenomena of ... ... 34

Author's argument, Summary of ... 141
Axiom of Hippocrates concerning

heredity ... ... ... ... 112

B.

Bacon quoted ... ... ... 9, 18

Bain, Dr., quoted ... ... So, 60, 62

Balfour quoted ... ... ... 19

Boucher quoted ... .. ... 134

Bright's disease of kidneys, Hereditary... 155

Barlow's, Dr., cases of hereditary cancer 101

Barlow, Dr. G. H., quoted ... ... 119

Bastian, Dr., quoted ... ... ... 129

Basis of morals — responsibility... ... 244

Bazin quoted ... ... ... ... 225

Bichat quoted ... ... ... 59

Biliousness, Heredity of ... 166, 170

Birch-Hirschfield quoted ... ... 192

Boerhaave quoted ... ... ... 134

Bricheteau quoted .. ... ... 137

Bronchocele diathesis ... ... ... 91

Buffon quoted ... ... . 61

Burdach quoted ... ... 48,245

Burzareingues, Girou de, quoted ... 61

c.

Caesar, Julius, quoted... ... ... 66

Cagots, Heredity amongst ... ... 67

Calderon quoted ... ... ... 246

Cancer, Heredity of ... ... ... 101

Cardiac diseases, are they heritable ? ... 119

Carlyle quoted ... ... ... 244

Carpenter, Dr., quoted 8, 31, 50, 77, 128, 236

Catarrh defined ... ... ... 150

Catarrhal diathesis ... ... ... 88

Catarrhal diathesis, Respiratory diseases

under ... ... ... ... 15!

Checks to inheritance ... ... ... 149

-Chorea, Heredity of ... ... ... 136

.Chlorosis, Heredity of... .. ... 188

Chylo-poietic system Diseases of, Heredi-
tary ... ... ... ... I59

Circulatory system, Heredity of diseases

of ... ... ... ... 114

Cirrhosis of liver, Hereditary ... ... 164

Cirrhotic disease of kidneys, Hereditary 156

Complexion, Inherited... ... ... 21

Congenital diseases of heart ... ... 116

Constitution, Sound, defined ... ... 153

Copland, Dr., quoted ... ... ... 134

Casauvieilh quoted ... ... ... 134

Cases, Why no two, exactly alike ... 108
Cause and effect underlie moral, as they

do physical and mental phenomena... 246

Causes of heart disease ... ... 117

Cephalalgia, Hereditary ... ... 128

Cerebration, Unconscious ... ... 34

Cerebral hemispheres, Functions of ... 49

Cerebral hypersemia, Heredity of ... 120

Character, Heredity in national ... 65

Character, Tenacity of national ... 66

Cheyne, Dr., quoted ... ... ... i.n

Congestion, Hepatic, Heredity of
Contagium, Definition of
Corpulence, Heredity of
Cretinism, Hereditary...

... 206
14, 166, 190
92

Crime and vice, Tendencies to, Inherited 245

D.

Darwinian theory
Darwin quoted
Deaf-mutism, Heredity of
Deficient vitality
Definition of instinct ...
Definition of pathology

19

19, 20, 21, 30, 37

45

153

37

7*

Degenerative vascular changes, Hereditary 120
Development of man's moral nature ... 243
Dr. Quatrefages quoted ... ... 24

Diabetes mellitus, Heredity of ... 193

Diabetes insipidus, Heredity of ... 194

Diatheses, Blending of ... ... 150

Diatheses, Causation of

Diatheses, Classification of ...

Diatheses, diet

Diatheses, Three great universal

Diathesis, Bronchocele

Diathesis, Catarrhal

Diathesis defined

Diathesis, Gouty

Diathesis, Haemorrhagic

Diathesis, Hepatic

Diathesis, Leprous

Diathesis, Causes of leprous ...

Diathesis, Malarial ...

Diathesis of morbid new growths

Diathesis of premature senility

Diathesis, Rachitic ...

Diathesis, Rheumatic

Diathesis, Scorbutic ...

Diathesis, Scrofulous and tubercular ...

Diathesis of skin affections ..

Diathesis of vascular adynamia

Differentiation of individuals owing to

variability

Differentiation of individuals ..
Differentiation, Pathological ...
Diptheria, Causes of ...
Direct heredity

Disease as affected by temperament
Disease as affected by idiosyncrasy
Disease, Amyloid of kidney, hereditary
Disease, Bright's, hereditary ..
Disease, Cirrhotic, of kidney hereditary
Disease defined

Disease and health coeval with humanity
Disease immunities may be produced ...
Disease tendencies, Heredity of, not

invariable

Disease tendencies, Latency of
Disease tendencies, Peculiarities

transmissible

Disease tendencies may be neutralised ...
Diseases, Hereditary, all not alike
Diseases, acute infectious, Heredity of
Diseases, acute infectious, Classification

of

Diseases of chylo-poietic system, He-
redity of ...

Diseases, Causes of variation in
Diseases of circulatory system, Heredity

of ... ... ;..

Diseases, Differentiated

Diseases during uterine existence 105, 106, 107

Diseases and derangements of women,

Hereditary ... ... ... 158

Diseases of ear, Heredity of ... ... 212

Diseases of eye, Heredity of ... ... 210

Diseases of heart, Congenital ... 116

Diseases of heart and blood vessels . 119
Diseases, Hereditary, formulated . in
Diseases of kidneys, Hereditary .. 152

Diseases of liver, Hereditary .. ... 163

Diseases, Malarial-infectious ... ... 202

Diseases of nervous system, Hereditary 121
Diseases not entities ... ... ... no

Diseases of nutrition, Heredity of ... 184
Diseases of organs of special sense ... 210

82

Diseases of respiratory organs, Heredity

85

of .. ... ... ... 142

93

Diseases, Respiratory, included under

90

catarrhal diathesis ... ... 151

Diseases, Respiratory, included under
scrofulous diathesis ... ... 151

82
93

Diseases of skin, Heredity of ... ... 216
Diseases of skin, Classification of ... 219

95

Diseases of skin, Causes of ... 220, 221

102,

172
96
97

Diseases vary little in intensity ... 109
Dropsy, Heredity of ... ... ... 160
Dyspepsia, Heredity of ... 128, 160

90

99

102

E.

'98,

l82

87
98

Ear, Heredity of diseases of ... ... 212
Eccheverria quoted ... ... 133, 135

85

Eczema, Heredity of ... ... ... 224

102

Embryonic vesicle ... ... ... 11

102

Entities, Diseases not ... ... no

r tO

69
109

Epilepsy, Heredity of ... .. 133
Epistaxis, Heredity of ... .. 120
Erb, Professor, quoted ... ... 130

140

Erysipelas, Causes of ... ... 199

199

3

Esquirol quoted ... ... 122, 134
Evolution and heredity contrasted ... 5
Evolution, Theory of ... ... ... 19

80

Evolution and heredity interdependent

ary

156

and inseparable ... ... ... 23

ary

:ii

Exceptions of disorders of nutrition to
heredity ... ... ... ... 186

71

Experience, Modern, regarding heredi-

nity
not

145
i48

tary proclivities ... ... ... 112
Eye, Heredity of diseases of ... ... 210

104

£•

152

F.

[ ["t

113

T-lR

Factors of individuality ... ... 69

140

no

Faculties of intellect ... ... 50

fOf

195

Fcetal diseases in utero ... 105, 106, 107
Fmtor oris. Hereditv of . 160

195

159
109

114
71

Family likenesses ... ... ... 12

Fatty degeneration ... ... ... 166

Fatty infiltration ... ... ... 166

Fauconneau-Dufresne quoted ... 166

Forbes, Sir John, quoted ... ... 71

Formation, Peculiarities of, transmissible 113

Formula of hereditary diseases ... in

Fothergill, Dr. Milner, quoted 119, 171

Fox quoted ... ... ... ... 137

Fox, Dr. Tilbury, quoted ... 219, 220, 222

Free-will and heredity ... ... 242

Free-will and fate ... ... ... 244

Fuller, Dr., quoted ... ... ... 180

Functions of cerebral hemispheres ... 50

G.

Gall-stones, Heredity of ... ... 166

Garrod, Sir Alfred, quoted ... 177, 178, 180

Gaubius quoted by Steinau .. ... 158

Generation of Life, a mystery ... ... 10

GENERAL SUMMARY ... ... 231 — 242

Germs, Specific ... ... .. 196

Germs, Specific, Selective capacity of ... 197

Goethe quoted .. ... ... 6

Gouty diathesis ... ... ... 93

Gout, Heredity of ... ... 174,177

Gouty or fibrotic disease of kidneys,

Hereditary ... ... ... 156

Gout, Rheumatic, Heredity of... 180, 181

Grandidier quoted ... ... ... 95

Granville, Dr. Mortimer, quoted 36, 51

Green, Dr., quoted ... ... 71, 100

Griesinger quoted .. ... 129,204

Growths, New, Diathesis of morbid ... 99

Gull, Sir William, quoted ... ... 125

Gypsies, Heredity amongst ... ... 67

H.

Hair and teeth, Correlation between ,.. 218
Hardy quoted ... ... ...'226

Hartmann quoted ... ... ... 37

Haemophilia, Specifically hereditary ... 120
Haemorrhagic diathesis ... ... 95

Health and disease coeval with humanity 145
Hearing, Heredity of sense of ... ... 44

Heart disease, Causes of ... ... 117

Heart diseases— are they heritable ? ... 119
Heart, Congenital diseases of .. ... 116

Heart, Intermittent action of, Hereditary 120
Hemispheres, Cerebral, Functions of ... 50
Hepatic diathesis ... ... 102,172

Heredity of abnormal distribution of

radial artery

Heredity of abnormal moral habits
Heredity of acne

Heredity of acute and chronic gout
Heredity of acute and chronic nephritis
Heredity of acute and chronic rheumatism
"Heredity of alcoholism
Heredity of anaemia ...
Heredity of apoplexy ..
Heredity of amyloid disease of kidneys..
Heredity, an effect of generation
Heredity appreciated by Greeks, Spar

tans, and Romans
Heredity amongst Jews, Gypsies, and

Cagots ...

Heredity of biliousness
Heredity of Bright's disease ..
• Heredity of cancer
Heredity of cephalalgia
Heredity of chorea
Heredity of diseases of chylo-poietic

system

Heredity of Cretinism...
Heredity of chlorosis ...
Heredity of corpulence or obesity
Heredity of deaf-mutism
Heredity defined
Heredity of diabetes mellitus ...
Heredity of diabetes insipidus ...
Heredity of diathetic diseases of chylo

poietic system ... ... ... 159

120
120
223
177
155
174
I3S

67
1 66, 170
••• 155
... 101
... 128
136

92

. 188

. 190

45,47

5

• 193
. 194

Heredity of diseases of circulatory system 114

Heredity, Direct ... ... ... 25

Heredity of disease tendencies not invari-
able ... ... ... .. 104

Hereditary diseases formulated ... m
Heredity of diseases and derangements

of women ... ... ... 158

Heredity of diseases of ear ... .. 212

. Heredity of diseases of eye ... ... 210

Heredity of diseases of heart ... ... 119

* Heredity of diseases of locomotive appa-
ratus ... ... ... ... 174

Heredity of diseases of nervous system... 121
Heredity of diseases of respiratory system 142

Heredity of diseases of skin ... ... 216

Heredity of disorders of nutrition ... 184

Heredity of dropsy ... ... ... 160

Heredity of dyspepsia... ... 128,160

Heredity of eczema ... ... ... 224

Heredity of epilepsy ... ... ... 133

Heredity of epistaxis ... ... ... 120

Heredity and evolution interdependent

and inseparable ... ... ... 23

Heredity of foetor oris ... ... 160

Heredity of fatty degeneration ... 166

Heredity of fatty infiltration ... ... 166

Heredity and free-will... ... .. 242

Heredity of gall-stones ... ... 166

Heredity of gout ... ... ... 177

Heredity governs man in his every aspect 247

Heredity of haemorrhoids ... ... 160

Heredity of helminthiasis ... ... 160

Heredity of hepatic diseases ... ... 163

Heredity of hepatic congestion 166, 168

Heredity of hernia ... ... ... 160

Heredity of hysteria ... ... ... 131

Heredity of ichthyosis . . . 226

Heredity of imagination ... ... 54

Heredity, Incorrect conceptions of ... 46

Heredity of Influence ... ... 28

Heredity, Indirect ... ... .. 27

Heredity, Influence of, to be traced far

back ... .. ... ... 145

Heredity of insanity ... ... ... 122

Heredity of intermittent action of heart 120

Heredity of intellect ... ... •• 58

Heredity of instinct ... ... ... 38

Heredity, Individual ... .. ... 23

Heredity of jaundice ... ... ... 166

Heredity of kidney diseases ... ... 152

Heredity, Laws of ... ... ... 24

Heredity, Latent ... ... •• 29

Heredity, Law of, coeval with humanity 145

Heredity, Law of inexorable ... ... 246

Heredity of longevity ... ... ... 128

Heredity of left-handedness ... 16, 43

Heredity of likeness in disease... ... 70

Heredity of man's moral nature 242, 245

Heredity, Mediate and immediate ... 29

Heredity of memory ... ... ... 54

Heredity of mollities ossium ... _ ... 183
Heredity, Moral, a sort of psychical

heredity ... ... ... ... 245

Heredity in national character... ... 65

Heredity of neuralgia... ... ... 130

Heredity of neuropathic predisposition ... 129

14

... 210

... i83
70—231

.. 213
... 215

. 215

41

...7—30

12

... 103
142

Heredity of obesity ...
Heredity of organs of special sense
Heredity of osteo-malakia
HEREDITY, PATHOLOGICAL
Heredity of peculiarities of touch
Heredity of peculiarities of taste
Heredity of peculiarities of smell
Heredity of perceptive faculties
HEREDITY, PHYSIOLOGICAL
Heredity, Physiological, Causes of
Hereditary predisposition, Meaning of ...
Hereditary predisposition of tissue
Hereditary proclivities, Modern experi-
ence regarding ... ... ... 112

Heredity of progressive pernicious anaemia 189

Heredity of psoriasis ... ... ... 225

HEREDITY, PSYCHOLOGICAL ... 31 — 67

Heredity of pulmonary phthisis ... 143

Heredity of rachitic diathesis ... .. 182

Heredity of reason ... ... .. 58

Heredity of renal and vesical calculus . . 157

Heredity of ringworm... ... . . 222

Heredity of rheumatic gout ... . . 180

Heredity of scrofulosis ... .. 191

Heredity of sentiments and passions . 59

Heredity of special senses .. . . 41

Heredity, Specialised or initial... ... 28

Heredity of suicidal tendency ... ... 122

Heredity of tendencies to vice and crime 245

Heredity of varicose condition of veins 120

Heredity, Vicarious ... ... ... 162

Heredity of the Will 62

Hoffmann, F., quoted ... . . 157

Hertz quoted .. ... ... ... 204

Hirschfield- Birch quoted ... ... 192

Hirsch quoted ... ... 143, 146

Horlin quoted ... ... ... 146

Horace quoted ... ... ... 6

Hippocrates, Axiom of, concerning

heredity ... ... ... ... 112

Hyperaemia, Cerebral, hereditary ... 120

Hutchinson, Mr. Jonathan, quoted, 80, 81, 82,

85, 89, 93, 94, 95, 97, 98, 99, 100, 102, 150,

172, 183, 184, 197, 199, 201, 223, 226, 228,

229, 231, 238.

I.

226
166
So
15
43
27
67

Ichthyosis, Heredity of

Icterus, Heredity of ...

Idiosyncrasy as affecting disease

Idiosyncrasies, Heritable

Idiosyncrasies of touch

Indirect heredity

Individuality of man ...

Individual differentiation owing to varia

bility ... p

Individual pecularities ... ... *0

Individuals, no two alike physically or

mentally ... ... ... ... 67

Individuality, Analysis of man's ... 68

Individuality, Factors of ... ... 69

Individuality as affecting morbid processes 72
Individuality, Intra-uterine factors of ... 108

Individual differentiation ... ... 109

Individuals, Unlikeness of ... ... 127

Individual heredity ... ... ... 23

Individuality of man, in every aspect,

subject to heredity ... ... 247

Influence, Heredity of ... ... 28

Imagination, Heredity of ... ... 54

Immermann quoted ... 96, 185, 186, 190

Immediate heredity ... ... .. 29

Infectious acute diseases, Heredity of ... 195

Infectious acute diseases, Classification of 195

Infectious diseases, Malarial ... ... 202

Inheritance of acquired modifications ... 15

Inheritance, Checks to ... ... 149

Inheritance of complexion ... ... 14

Inheritance of congenital malformations 17

Inheritance of fecundity ... ... 15

Inheritance of lefthandedr.ess ... ... 16

Inheritance of likeness in disease ... 70

Inheritance of longevity ... ... 15

Inheritance of obesity... ... ... 14

Inheritance of physical peculiarities ... 12

Initial heredity ... ... ... 28

Intellect, Definitions of ... ... 56

Intellect, Faculties of ... ... ... 50

Intellect, Heredity of ... ... 58

Intellect, Noumenal ... ... ... 56

Intellect, Phenomenal... ... ... 56

Intellect, Unity of ... ... ... 57

Insanity, Heredity of ... ... ... 122

Instinct defined .. ... ... 37

Instinct, Hereditary ... ... ... 38

Instinct, Innateness of ... ... 39

Instinct and intelligence ... ... 39

Instincts, Origin of ... ... ... 40

Instincts, natural and acquired ... 38

Intermittent action of heart, Hereditary 120

Insusceptibility and predisposition 207, 208

aundice, Heredity of .. 166, 167

eftichjew, Andrian, Case of .. ... 217

eftichjew, Fed or, Case of .. .. 217

ews, Heredity amongst the .. -67

ohnson, Dr. George, quoted .. . 157

oily quoted ... ... .. . 132

ones, Dr. Macnaughton, quoted . 212

ulius Caesar quoted ... ... . 66

K.

Kirkes, Dr., quoted ... ... 42, 50

Kidneys, diseases of, Hereditary ... 152

L.

Lamarckian Axiom ... ... ... 6

Lambert, Case of Edward ... 26, 216

Latency of disease-tendencies . 105,152

Latent heredity ... ... ... 29

Laws of heredity ... ... ... 24

Law of heredity coeval with humanity ... 145

Law of heredity inexorable ... ... 246

Laws of Manu quoted ... ... 6

Law, Mosaic, quoted ... ... ... 6

Laws, Natural, defined ... ... 8

Laws, Natural, mysterious ... ... 9

Law of pleasure and pain . ... 60

Law of self-conservation ... .. 60

Laycock, Dr., quoted ... . ... 87

Lebert quoted ... ... ... 208

Lefthandedness, Heredity of ... 16,43

Leprous diathesis ... ... .. 96

Leprous diathesis, due to fish .. ... 97

Leichtenstern quoted ... ... 164, 206

Lesser quoted .. ... ... 227

Leube quoted... ... ... ... 137

Lewis, Mr., quoted ... ... ... 8

Life, a curse to many ... ... ... 247

Likeness in disease, Inheritance of ... 70

Likeness, Exact, never transmitted ... 187

Likenesses, Family ... ... ... 12

Liver, Diseases of, hereditary ... 163
Locomotive apparatus, Heredity of

diseases of ... ... ... 174

Longevity, Hereditary ... ... 128

Lucas, Dr. Prosper, quoted ... 27, 42, 214

Lusitanus, Zacutus, quoted ... ... 134

M.

Maclagan, Dr., quoted 87, 174, 175, 203

Macnaughton Jones quoted .. ... 212

Malarial diathesis ... ... ... 90

Malarial infectious diseases ... ... 202

Man, Individuality of. ... ... 67

Man's individuality, Analysis of ... 68

Man, a complicated being ... ... 146

Man, much the same in every age ... 145
Man, subject to heredity, in every aspect

of his individuality ... ...

Manu, Sacred laws of, quoted ... ...

Materialistic definition of intellect ...
Maudsley, Dr., quoted

13, 18, 29, 52, 104, 122, 148, 152

Mediate heredity ... ... ... 29

Memory defined ... ... 50

Memory, a form of habit ... ... 52

Memory inherited ... ... ... 54

Meniere, Dr. quoted ... _ ..; ... 45

Mental characteristics transmissible ... 36

Metamorphoses in transmission ... 123

Metamorphoses in transmission, what are

they? ... ... ... ... 126

Miasmatic contagious diseases... ... 205

Miasmatic contagious diseases, classifi-

cation of... ... ... ... 206

Miasm, Definition of ... ... .. 206

Mind dependent on brain ... ... 35

Mivart quoted ... ... ... 9

Morals, Basis of, responsibility ... 244

Moral habits, Heredity of abnormal ... 129

MORAL HEREDITY ... ... ... 242

Moral Heredity, a form of psychical

heredity ... ... ... ... 245

247
6

56

246

247

247

158

27

III

Moral nature of man, Development of ... 243
Moral nature of man, hereditary ... 245

Moral phenomena, subject to cause and

effect

Moral responsibility ...
Morally responsible, All men ...
Montaigne, Case of
Montaigne quoted

Morbific predisposition may be dormant
Morbific predisposition may be neutra-
lised .. ... ... ... in

Moreau, Dr., quoted ... ... 46, 124, 125

Morel, Dr., quoted ... ... ... 46

Mortimer, Granville, Dr., quoted ...36,51

Mosaic law quoted ... ... ... 6

Miiller quoted ... ... ... 52

N.

National character, Heredity in ... 65

National character, Tenacity of ... 66

Natural laws defined 8

Natural laws inexorable ... ... in

Natural laws, mysterious ... ... 9

Nature, Moral, of man hereditary ... 245

Nephritis, Acute and chronic, hereditary 155
Nervous system, Diseases of, hereditary

121, 140

Neumann quoted ... ... ... 225

Neuralgia, Heredity of ... ... 130

Neutralisation of inheritance ... ... 149

Neuropathic predisposition, Heredity of 129

Niemeyer, Dr., quoted ... ... 91

Nothnagel quoted ... ... 134, 135

Nutrition, Disorders of, hereditary ... 184
Nutrition, disorders of, Exceptions to

heredity of ... .. ... 185

Nutrition, Predisposition to disorders of 185

O.

Obesity, Heredity of ... ... 14, 166, 190

Ord, Dr., quoted . ... ... 103

Organs and tissues, all human hereditary 154
Organs of special sense, Heredity of . . 210
Oris fcetor, Heredity of ... ... 160

P.

Paget, Sir James, quoted

70, 73, 102, 149, 169, 208
Parallelism between Physiology and

Psychology ... 31

Pastrana Julia, Case of ... ... 218

Pathological differentiation ... ... 140

PATHOLOGICAL HEREDITY ... 70 — 231

Pathology defined ... ... ... 71

" Pathology " Dr. Green's, quoted ... 71
Peculiarities of disease-tendencies,

transmissible ... .. ... 113

Peculiarities of formation, transmissible 113

Peculiarities, heritable, of taste ... 215

Peculiarities, heritable, of touch ... 213

Peculiarities, heritable, of Smell ... 215

Perceptive faculties, hereditary ... 41

Phenomena of the affections ... ... 60

Phenomena of automatism ... ... 34

Phenomena sensible, Spinoza's theory of 59

Phthisis pulmonary, heredity of ... 143

Physiological causes of heredity ... 12

Physical heredity ... ... ... 7

PHYSIOLOGICAL HEREDITY ... ...7—30

Physical peculiarities inherited ... 12

Pleasure and pain, Law of ... ... 60

Pollock, Dr., quoted ... ... ... 146

Portal quoted ... ... ... 121

Powell, Dr. Douglas, quoted ... 152, 154

Predisposition? What is meant by ... 73

Predisposition, Hereditary ... ... 73

Predisposition, Acquired .. ... 76

Predisposition, JEta.1 ... ... ... 74

Predisposition to disorders of nutrition 185

Predisposition, hereditary, of tissue ... 142

Predisposition and insusceptibilitj' 207, 208

Predisposition, meaning of ... ... 103

Predisposition morbific, may be dormant in
Predisposition morbific, may be neutralised 1 1 1

Predisposition neuropathic, hereditary 129

Predisposition to respiratory diseases ... 152

Predisposition, Sexual ... .. 75

Progressive pernicious anaemia, here-
dity of ... ... ... ... 189

Psoriasis, heredity of ... ... 225

PSYCHOLOGICAL, HEREDITY ... 31—67

Psychological phenomena ... ... 36

Quatrefages, De, quoted

R.

Rachitic diathesis ... ... 98, 182

Radial artery, Abnormal distribution of

hereditary ... ... ... 120

Reason, Cousin and Reid's definition of 58

Reason, Hereditary ... ... ... 58

Reininger quoted ... ... ... 134

Renal Calculus, hereditary ... ... 157

Respiratory organs, Diseases of, heredi-
tary ... ... _ ... ... 142

Respiratory diseases subject to catarrhal

diathesis... ... ... ... 151

Respiratory diseases subject to scrofu-
lous diathesis ... ... ... 151

Respiratory diseases, Predisposition to 152

Responsibility, The basis of moral ... 244

Responsible, All men morally... ... 247

Responsibility, Moral ... ... 247

Reversional heredity ... ... ... 27

Reversion, Tendency to, of variations of

specific characters ... .. 148

Reynolds, Dr. Russell, quoted 133, 136

Rheumatic diathesis ... ... ... 87

Rheumatism, acute and chronic,

Heredity of ... ... ... 174

Rheumatic gout, Heredity of ... ,,. 180

Ribot quoted, 5, 14, 23, 26, 29, 30,, 34, 35, 37,

39, 41, 43, 45, 53, 55, 57, 58, 59, 60, 64, 65,

122, 124, T27, 211, 212, 243, 244, 245

Richardson, Dr. B. W., quoted,

107, 108, 112, 121, 139

Richter quoted ... ... ... 137

Ringworm, Heredity of ... ... 222

Rittershain, Von, quoted ... ... 183

Roberts, Dr. F. T., quoted ... ... 170

Rokitansky quoted ... 166

Ruehle quoted ... ... 144,147

s.

Schiller quoted ... ... ... 246

Schopenhauer's theory of intellect ... 57
Schwimmer, Professor Ernst, quoted ... 229
Science, Office of defined ... ... 8, 32

Science -versus Theology ... 242,243

Scorbutic diathesis ... ... ... 98

Scrofula defined ... ... ... 150

Scrofulous diathesis ... ... . . 85

Scrofulosis, Heredity of ... .. 191

Self- conservation, Law of ... . . 60

Senator quoted ... ... . . 194

Sensorial qualities hereditary ... .. 41

Senility premature, Diathesis of . . 102

Sight, Heredity of sense of ... ... 43

Skin diseases, Causes of ... 220, 221

Skin diseases, Classification of ... 219

Skin, Heredity of diseases of ... ... 216

Skin Affections, Diathesis of ... ... 102

Smee, Dr., quoted ... ... 37, 51

Smell, Heredity of sense of ... ... 48

Smell, Heritable peculiarities of ... 215
Smith, Dr. Alder, quoted ... ... 222

Specialised heredity ... ... ... 28

Specific characters, Tendency to rever-
sion of variations of ... ... 148

Special sense, Heredity of organs of ... 210
Special senses considered ... ... 41

Species, Origin of ... ... ... 41

Spontaneous differences ... .. 7

Spencer, Mr. Herbert, quoted... 37, 40, 43
Spinoza's theory of sensible phenomena 59
Stahl quoted ... ... ... 134,210

Statistics of heredity of hepatic disease 164
Steinau quoted ... ... 106, 161, 211

Suicidal tendency, Heritable ... ... 122

Summary as to heredity of hepatic disease 173
SUMMARY, GENERAL ... ... 231-242

Summary of author's argument ... 141

Summary of skin diseases 227,228, 229,230,231
Sutton, Dr. H. G., quoted ... ... 191

Syphilis ... ... ... ... 200

T.

Tanner, Dr. quoted ... ... ... 75

Taste, Heredity of sense of ... ... 48

Taste, Heritable peculiarities of ... 215

Teeth and hair, Correlation between ... 218

Temperament, as affecting disease ... 78

Tenacity of national character ... 66

Tendencies to vice and crime, Inherited 245
Tennyson quoted ... ... ... 246

Theology versus Science ... 242,243

Thierfelder, Professor, quoted .- 169

Thought, a mystery ... ... ... 57

Tilbury Fox, Dr., quoted ... 219, 220, 222
Tissues and organs, all human, hereditary 154
Touch, Heredity of sense of ... ... 42

Touch, Heritable peculiarities of ... 213
Touch, Idiosyncrasies of sense of ... 43
Transformation in transmission ... 123

Transformation in transmission. What

does it mean ? ... ... ... 126

Trousseau quoted ... ... ... 184

Tuberculosis, Heredity of ... ... 191

Tubercular diathesis .. ... ... 85

u.

Unconscious cerebration
Unity of intellect
Universal diatheses. Three
Unlikeness of individuals

Uterine existence, Diseases during

105, 106, 107
Uterine -intra factors of individuality ... 108

V.

Variability, Law of, causing differentia-
tion of individuals ... 68, 209
Variation, Principle of ... ... 18

Variation, Tendency to ... ... y

Variation in disease, Causes of ... 109

Varicose condition of veins, hereditary 120
Variations of specific characters,

Tendency to reversion of ... ... 148

Vascular adynamia, Diathesis of ... 102
Vascular diseases, are they heritable ?... 119
Vascular degenerative changes, Here-
ditary ... ... ... ... 120

Veiel, Drs., quoted ... ... ... 225

Vesical calculus, hereditary ... ... 157

Vesicle embryonic ... ... ... n

Vicarious heredity ... ... ... 162

Vice and crime, Tendencies to inherited 245

Vitality, Deficient ... ... ... 153

Voltaire quoted ... ... ... 64

w.

Weyl, Dr., quoted ... ... .. 225

Will defined 62

Will, Heredity of the 62

Will, Instances of heredity of the ... 62

Williams, Dr Theodore, quoted ... 147
Women, diseases and derangements of,

Hereditary ... ... ... 158

Ziemssen's, Prof., Cyclopaedia, quoted

130, 132, 137, 138, 144, 147
Zacutus Lusitanus quoted ... ... 134

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