CHAPTER III

HEREDITY AND ATAVISM

Heredity, like other biologic factors, starts with the cell. As elsewhere pointed out, reproduction is first unicellular in type and involves an expenditure of nutritive force antagonistic to the growth of the cell. As Geddes remarks,[66] no one can dispute that the nutritive, vegetative, or self-regarding processes within the plant or animal are as opposed to the reproductive, multiplying, species-regarding processes, as income to expenditure or as building up to breaking down. But within the ordinary nutritive or vegetative functions of the body there is necessarily a continuous ant.i.thesis between two tissue-changing sets of processes, constructive and destructive metabolism. The contrast between these two processes is seen throughout nature, whether in the alternating phases of cell-life or in the great ant.i.thesis of growth and reproduction.

The starfish, deprived of an arm, replaces this by a fresh growth; crabs can renew the great claws which they have lost in fighting; even as high up as the lizard the loss of a leg or a tail can be made good. In a great variety of cases a kind of physiological forgiveness is shown in the reparation of even serious injuries. Now this "regeneration," as it is called, is a process of reproduction. By continuous growth the cells of a persistent stump are able to reproduce the entire number. A sponge, a hydra or a sea-anemone may be cut into pieces with the result that each fragment grows into a new organism. The same is done with many plants; and though the division is artificial the result shows how very far from unique is the process spoken of as reproduction, which is but more or less discontinuous growth. This is well shown in the evolution onward insensibly from cases of continuous budding, as in sponge or rosebush, to discontinuous budding in hydra zoophyte and tiger-lily, where the offspring vegetatively produced are sooner or later set free.

The enormous expenditure of force required for unicellular reproduction is lessened by conjugation with another cell through satisfaction of cell hunger; and this, by making two cells do the work of one, lessens the amount of nutritive force expended by each. Evolution in fertilisation has the following steps:--

I. Formation of plasmodia.

II. Multiple conjugation.

III. Conjugation of the two similar cells.

IV. Union of incipiently dimorphic (different) cells.

V. Fertilisation of differentiated s.e.x elements.

As Maupas has shown, by the time conjugation of two similar cells is reached, the paranucleus in both is incipiently hermaphroditic. The impelling force leading to conjugation is, as Rolph has shown, cell hunger. Conjugation, he remarks, is a necessity for satisfaction, a gnawing hunger which drives the animal to engulf its neighbour, to isophagy (self-eating). The process of conjugation is only a special form of nutrition which occurs because of a reduction of the nutritive income or an increase of the nutritive needs. It is an "isophagy" which occurs in place of "heterophagy" (eating of others). "The less nutritive, and therefore smaller, hungrier, and more mobile organism is the male, the more nutritive and usually relatively more quiescent organism the female.

Therefore, too, is it that the small starving male seeks out the large, well-nourished female for purpose of conjugation, to which the latter, the larger and better nourished, is on its own motive less inclined." The unicellular type of reproduction long remains after s.e.x differentiation has occurred and a.s.sumes the form of parthenogenesis (virgin generation).

The phenomena of this demonstrate that the female element is the highest in evolution. Spitzka[67] has shown that the ovum possesses an inherent activity independently of fructification. How far this may extend in the direction of more mature development is shown by what is known about parthenogenesis. This is the development of living beings without a father. Bees, some b.u.t.terflies, ants and wasps notoriously multiply their kind without s.e.xual congress. As a rule the parthenogenetic offspring are themselves incapable of further procreating their kind. But to this there are remarkable exceptions. The aphides multiply for many generations without the intervention of a male. Weigenbergh has shown that the silk-moth can be propagated as long as the male element is permitted to act at every fourth generation. The _Artemsia salina_, a minute crustacean living in saline springs, reproduces its kind for years without a male being present, males being produced at definite intervals only (Von Siebold). Among the vertebrata parthenogenetic development has also been observed, though rarely reaching maturity. Thus, segmentation occurs in unfertilised ova of the chicken (Oellacher), of the fish (Burnett and Aga.s.siz), and of frogs (Moquia-Tanden). Spitzka has seen a blastoderm form in unfertilised ova of the toad-fish (_Batrachus tau_).

Hensen isolated the oviducts of a rabbit, thus rendering the admission of s.e.m.e.n impossible, while the ova, discharged at heat, were compelled to remain in these oviducts. Three years later he killed the animal and found the ova had developed into twisted, club-shaped, hollow sacs. The development in the female ovary (also, though very rarely, in the male t.e.s.t.i.c.l.e and parotid gland, which show such a remarkable metastatic sympathy in mumps), of dermoid cysts (containing bones recognisable as maxillaries with teeth, hair, and skin, rudimentary bowel, gland, and brain traces), even in undoubted virgins, proves that even the human ovum is capable of parthenogenetic development. While such development, so far as known to science, is always abortive, and while, as Washington Irving remarks, the ingenious maiden who to-day would attribute conception to any other cause than s.e.xual congress would find it difficult to overcome the prejudice of scientists, yet embryology, while declaring immaculate generation improbable, does not p.r.o.nounce it impossible. A worker bee may be an offspring of an unimpregnated queen bee. What is a regular occurrence in one cla.s.s of animals is sometimes observed as an exceptional one in another cla.s.s. If the startling and apparently miraculous nature of a virgin generation of a living child be regarded as the sole objection to receiving such a fact, its defender might urge that the virgin generation of a dermoid cyst with all the traces, however aborted, of vertebrate organisation, is only a shade less startling and miraculous.

This power of parthenogenesis, however, cannot continue indefinitely without extinction. This has been shown by the careful experiments of Maupas, who had observed 215 generations of an infusorian without s.e.xual union. He found that then the family became extinct. Powers of nutrition, division, and conjugation with unrelated forms come to a standstill. The first symptom of this senile degeneration is decrease in size, which may go on till the individuals only measure a quarter of their normal proportions. Various internal structures then follow suit "until at last formless abortions occur, incapable of living and reproducing themselves."

The nuclear changes are no less momentous. The important paranucleus is fatally sterile. The larger nucleus may also become affected, "the chromatin gradually disappears altogether." Physiologically, too, the organisms become manifestly weaker, though there is excessive s.e.xual excitation. Such senile decay of the individuals and of the isolated family inevitably ends in death. s.e.xual union in those infusorians, dangerous perhaps for the individual life, a loss of time so far as immediate multiplication is concerned, is, in a new sense, necessary for the species. The life runs in cycles of a s.e.xual division which are strictly limited. Conjugation with unrelated forms must occur else the whole life ebbs. Without it the protozoa, which some have called "immortal," die a natural death. Conjugation is the necessary condition of their eternal youth and immortality.

Starting from this standpoint the relative functions of the two s.e.xes in heredity are apparent. The original function of reproduction, that of cell division, is the part of the female. The male in the lower instances simply supplies the female with nutriment. Thus in certain plants there is nothing but a subtle osmosis between the s.e.xes. This is also the case with some of the lower infusoria. With a rise in evolution protoplasm becomes differentiated. At the outset of the subject of heredity it is evident, therefore, that the female furnishes the type which is best capable of development when properly nourished by a highly developed male. To deficiencies in both particulars are due defects and variations in the offspring. As the product of fructification is longest under the nutritive control of the female, her influence is most emphatic in either redeeming defects or producing them. Heredity, according to Ribot, Spitzka, Fere, and others, is divisible into direct heredity, indirect heredity, and, more dubiously, telegony. Direct heredity consists in the transmission of paternal and maternal qualities to the children. This form of heredity has two aspects: (1) The child takes after father and mother equally as regards both physical and moral characters, a case strictly speaking of very rare occurrence; or (2) the child, while taking after both parents, more especially resembles one of them. Here again distinction must be made between two cases. The first of these is when the heredity takes place in the same s.e.x from father to son, from mother to daughter. The other which occurs more frequently, is where heredity occurs between different s.e.xes--from father to daughter or from mother to son. Reversional heredity or atavism consists in the reproduction in the descendants of the moral or physical qualities of their ancestors. It occurs frequently between grandfather and grandson, as well as between grandmother and granddaughter. Collateral or indirect heredity, which is of rarer occurrence than the foregoing, and is simply a form of atavism, subsists, as indicated by the name, between individuals and their ancestors in the indirect line--uncle, or grand-uncle and nephew, aunt and niece. Finally (3) there is telegony, or the heredity of influence, very rare from the physiological point of view, which consists in reproduction in the children by a second marriage of some peculiarity belonging to a former spouse.

In dealing with heredity the position of Weismann and others, that acquired characters cannot be inherited, needs a short examination. In his later work Weismann has practically abandoned the essential basis of his position by admitting that maternal nutrition may play a part in determining variation. He[68] now a.s.serts that the origin of a variation is equally independent of selection and amphimixis, and is due to the constant occurrence of slight inequalities of nutrition in the germ plasm.

As acquired characters affecting the const.i.tution of the parents are certain to affect the nutrition of the germ plasm, it is therefore obvious, according to Weismann's admission, that acquired characters or their consequences will be inherited. This is an emphatic though concealed abandonment of the central position of Weismann.

One of the stock arguments of the Weismann school is drawn from results of the Jewish rite of circ.u.mcision. While the operation is not calculated to make a profound impression on the const.i.tution, and furthermore, as being performed on the male, less likely to affect the race, still the alleged non-inheritance of its results is much over-estimated. William Wolf,[69]

of Baltimore, Maryland, who has circ.u.mcised six hundred Jewish children, finds on careful examination, that 2 per cent. were born partially circ.u.mcised and 6 per cent. were born with a short prepuce. P. C.

Remondino,[70] of Los Angeles, California, has seen a large number of cases of absence of the prepuce which proved to be hereditary. After a confinement his attention was once called to the child by the nurse, who thought it was deformed. The nurse was astonished at the size and appearance of the glans p.e.n.i.s. On examination the prepuce was found to be completely absent. On inquiry, the father and another son, born more than twenty years previously (comprising every male member of the family), were found to have been born with the glands fully exposed. He has seen a French family similarly affected.

Similar, but much stronger, results have been obtained by me through the courtesy of the Reverend Drs. S. Bauer, M. A. Cohen, and B. Gordon, all of Chicago. Dr. Bauer, who has been seventeen years in the practice of the religious rite of circ.u.mcision, has circ.u.mcised 3,400 boys and has found preputial absence in about 3-1/2 per cent. of the cases. Dr. Cohen, who has been two decades in the practice, has performed 10,000 circ.u.mcisions.

He has found the prepuce wanting in 500 cases; partially developed in 300 cases; slightly developed in 2,000 cases. Dr. Gordon has performed 4,400 circ.u.mcisions in twenty-five years. He has found the prepuce absent in 15 cases; partly wanting in 200, and slightly developed in 2,200 cases.

These, it should be remembered, are only cases where preputial change forced itself on the observer, who was not pursuing investigations on this point.

The volume of Hebrew casuistic religious literature collected in the Medrash, evidences as I have elsewhere[71] shown the frequency of congenital preputial defect.

That acquired characters can be transmitted has been definitely shown by the experiments of George Roe Lockwood,[72] of New York, anent hereditary transmission of mutilations. White mice were selected, as they begin to breed when thirty days old, and breed every thirty days. He bred in-and-in for thirty-six generations, destroying the weakly, and thus obtained finer animals than the first pair. He selected a pair, caged them by themselves, and clipped the tails of the young. When they were old enough to breed, he selected a pair and clipped the tails of their progeny. In the seventh generation he obtained some tailless mice, and finally a tailless breed.

The experiments have one possible element of error; white mice, like all albinoes, are a degenerate type. At the same time these experiments show that accidental mutilations favoured by circ.u.mstances are inherited.

Eimer[73] reports the case of a pair of long-tailed pointers which had once produced a litter of long-tailed pups. In order to obtain short-tailed pups the owner had the tails of both shortened. The b.i.t.c.h from that time produced repeatedly short-tailed pups only. As the most careful attention was paid to the parents, no error can be suspected in this case, which, moreover, excites no surprise among dog-breeders.

Brown-Sequard[74] has shown that a peculiar alteration of the shape of the ear or a partial closing of the eyelids is inherited by the offspring of animals in which these changes were caused by dividing the sympathetic.

Exophthalmia (eye protrusion) was inherited by guinea-pigs in whose parents this protrusion of the eyes had occurred after an injury to the spinal cord, and so were bruises and dry gangrene, as well as other trophic disturbances in the ear, due in the parents to an injury to the restiform body of the brain. Loss of certain phalanges or of whole toes of the hind feet which had occurred in the parents in consequence of division of the sciatic nerve was inherited. Diseased conditions of the sciatic nerve occurred in the offspring of guinea-pigs in which this nerve was divided. Forty guinea-pigs in which one or both eyes showed more or less morbid change were descended from three individuals in which one eye had become diseased in consequence of transverse section of the restiform body. Twenty guinea-pigs exhibited muscular atrophy on the upper and lower sides of the thigh, when in the parents such atrophy had been caused by section of the sciatic nerve.

The experiments of Brown-Sequard, Westphal, Dupuy[75] and Obersteiner, which show that artificially induced epilepsy is inherited, still further bear out the conclusions resultant on the inheritance of these mutilations. Indeed, Weismann has been forced to that _reductio ad absurdum_ in science, narrowly limited definitions, in order to maintain his position. "But although I hold it improbable," he remarks, "that individual variability can depend on a direct action of external influences upon the germ cells and their contained germ plasm, because, as follows from sundry facts, the molecular structure of the germ plasm must be very difficult to change, yet it is by no means to be implied that this structure may not possibly be altered by influences of the same kind continuing for a very long time. This much may be maintained: that influences which are mostly of variable nature, tending now in one direction, now in another, can hardly produce a change in the structure of the germ plasm, and this is the reason why the cause of inheritable individual differences must be sought elsewhere than in these varying influences." "No one has doubted," he says, in reply to objections made by Virchow, "that there are a number of congenital deformities, birth-marks, and other individual peculiarities which are inherited. But these are acquired characters in the above sense. True, they must once have appeared for the first time, but we cannot say exactly from what causes; we only know that at least a great proportion of them proceed from the germ itself, and must therefore be due to alterations of the germinal substance. If Virchow could show that any single one of these hereditary deformities had its origin in the action of some external cause upon the already formed body (soma) of the individual and not upon the germ cell, then the inheritance of acquired characters would be proved. But this no one has yet succeeded in proving, often as it has been maintained."

The crucial test which Weismann demands is furnished by Dupuy,[76] who made one thousand experiments on guinea-pigs to the fifth generation, critically rejecting all results which did not correspond to the most rigid tests of direct heredity, excluding all instances of indirect heredity, however demonstrable. He found that certain lesions of the spinal cord, or the brain or the sciatic nerve, give rise in guinea-pigs to epilepsy.

In from three to six weeks after the operation an alteration in the nutrition takes place in an area of skin which is limited by a line starting from the outer canthus of the eye, and running to the median line on the upper lip, enclosing the nostril, thence backward enclosing the lower jaw, to the anterior portion of the shoulder to the median dorsal line, to the base of the ear and inner canthus of the eye. The alteration in nutrition occurs on the side corresponding to the injury. The pain, heat and cold sense disappear by degrees, while touch appears to be exalted. Very soon, tickling this zone of skin gives rise to twitchings limited to the muscles of the eye and the eyelids on the same side. Later, the muscles of the mouth and of the face are affected, still later the contractions become more general, until the whole side is the seat of convulsions, then the convulsions attack the other side also. When things have come to this point the convulsions precede by a very short time complete loss of consciousness. If the subject of experiment be white, it is found that there is paleness of the face, but in all cases there is little foam at the mouth and dilatation of the pupils. The animal sometimes utters a cry corresponding to the epileptic cry in the man. Not only are the convulsions identical with those in epileptic man, but there is also loss of consciousness, a state of torpor, stupor, and even sometimes insanity. When epilepsy is due to the destruction of the sciatic nerve, the foot of the affected side loses the two outer toes, so that the animal has only one toe, the inner. When young are born to such a parent or parents (for it matters not whether one or both of the parents have been operated upon), they have very often only one toe on the posterior foot. Sometimes, however, they have additional toes, which, in this case, are attached by a pedicle to the limb.

Those peculiarities observed in the parents are in all their details witnessed in the guinea-pigs hereditarily born toeless, who have developed epileptic phenomena. In Dupuy's cases not only is the epileptic tendency (of which Weismann gives a wholly imaginative microbic explanation) inherited, but the very stigmata (loss of toes) which mark development of the parental epilepsy.

E. D. Cope's[77] careful studies of the effects of impacts and strains on the feet of mammals are testimony difficult for Weismann to explain, since they also meet his requirements.

Weismann's admission of the inheritance of a tuberculous habit must logically, from the standpoint of degeneracy, be regarded as destroying his claims.

Kiernan has observed the case of a female cat in which brain mutilation had been induced to secure secondary cerebro-spinal degenerations. The mutilations were made under antiseptic precautions. The descendants of this cat had traces of the mutilation, and its results until the fourth generation, when the breed became extinct. This instance certainly fulfils all Weismann requirements.

In the Lambert family a skin deformity, the last result of degeneracy in previous generations, was transmitted. This peculiarity appeared first, according to Proctor,[78] in the person of Edward Lambert, whose whole body, except his face, the palms of the hands and the soles of the feet, was covered with a h.o.r.n.y excrescence. He was the father of six children, all of whom as soon as they had reached the age of six weeks presented the same peculiarity. The only one of them who lived transmitted the peculiarity to all his sons. For five generations all the male members of the family were distinguished by the h.o.r.n.y excrescence which had adorned the body of Edward Lambert.

Shwe-Maong, one of the hairless Burmese, when thirty years old had his whole body covered with silky hairs, which attained a length of nearly five inches on the shoulders and spine. He had four daughters, but only one of them resembled him. She had a son who was hairy like his grandfather. The case of this family ill.u.s.trates rather curiously the relation between the hair and teeth; for Shwe-Maong retained his milk teeth till he was twenty (when he attained p.u.b.erty); then they were replaced by nine teeth only, five in the upper and four in the lower jaw.

Eight of these were incisors, the ninth (in the upper jaw) being a cuspid tooth.

Certain motor expressions of disturbed functions are also inherited.

Galton describes the case of a man who, when he lay fast asleep on his back in bed, had the curious trick of raising his right arm slowly in front of his face, up to his forehead, and then dropping it with a jerk, so that the wrist fell heavily on the bridge of his nose. The trick did not occur every night, but occasionally, and was independent of any ascertained cause. Sometimes it was repeated incessantly for an hour or more. The gentleman's nose was prominent and its bridge often became sore from blows which it received. At one time an awkward sore was produced that was long in healing on account of the recurrence, night after night, of the blows which first caused it. His wife had to remove the b.u.t.tons from the wrist of his nightgown, as it made severe scratches, and some means were attempted of tying his arm. Many years after his death his son married a lady who had never heard of the family incident. She, however, observed precisely the same peculiarity in her husband; but his nose, from not being particularly prominent, has never as yet suffered from the blows. The trick does not occur when he is half asleep, as, for example, when he is dozing in his armchair, but the moment he is fast asleep he is apt to begin. It, as with his father, is intermittent, sometimes ceasing for many nights, and sometimes almost incessant during a part of every night. It is performed, as it was with his father, with his right hand.

One of his children, a girl, has inherited the same trick. She performs it likewise with the right hand but in a slightly modified form; for after raising the arm she does not allow the wrist to drop upon the bridge of the nose, but the palm of her half-closed hand falls over and down the nose, striking it rather rapidly, a decided improvement on the father's and grandfather's method. The trick is intermittent in the girl's case also, sometimes not occurring for periods of several months, but sometimes almost incessantly. These "tricks" suggest nocturnal epilepsy, however.

The face of a child is often fully developed, yet, owing to some of the const.i.tutional diseases, arrested development of the face at this point takes place. The second generation inherits this deformity, while the grandparents possess normally developed faces.

The following case came under my own immediate observation. The grandfather was in the habit of sitting in front of the fire with fingers locked together twirling the thumbs in one direction, and then occasionally knocking the thumb nails together. Two of his three sons inherited this habit; the third brother had the habit of biting his nails when in a fit of abstraction. The nephew of the last has a similar habit under the like conditions. The children of this nephew have in two instances shown a tendency to pick at the nails when in an unconscious state, from acute disease. The third child has a periodical tendency to do the same since it was four months old.

V. P. Gibney,[79] of New York, has reported a family consisting of father and mother, five children, and one grandchild. The father and mother are semi-ambidextrous. All of the children and the grandchild are semi-ambidextrous to an annoying degree; all of the movements which they perform with one hand are simultaneously performed by the other hand. The girls are obliged to use only one hand when dressing themselves, or when cutting patterns, and hold the other hand down by their side, because the two hands perform the same movements at the same time and would interfere with each other.

One factor in heredity concerning which there has been much dispute, and whose existence has been denied because of certain theories anent the nerve connection of the mother and foetus, is that of maternal impressions. As Fere[80] has shown, the foetus exhibits very decided reaction to sensory impressions on the mother. He cites cases of several women who, often in the midst of an ordinary dream, producing but very moderate excitation, not generally interrupting sleep, were awakened by foetal movements. The dreams had nothing of the nightmare which would cause sudden contraction under the influence of a terrifying idea. They were merely the ordinary phenomena of sleep. Mental changes of the mother hence excite motor reactions in the foetus, and, as with sensorial excitations, these reactions are stronger in the foetus than in the mother. The mechanism of these motor reactions is, Fere points out, obviously due to unconscious and involuntary movement of the muscle walls of the womb. The organisation of a morbid predisposition may be largely influenced by an accident accompanying conception or gestation. In some degenerates cannot be found a trace of hereditary defect. The fact cited explains how sensorial excitations or repeated and violent emotions in the mother during pregnancy give rise to profound nutritive troubles in the foetus, and especially in its nervous system. These congenitally degenerated beings (_ab utero_) can hardly be distinguished from those having direct heredity. A considerable number of cases of epilepsy, idiocy, &c., are recognised as having arisen from alcoholism in the mother. Psychic troubles in the mother may react upon the foetus in an a.n.a.logous way. The prominent facts which show the influence of the psychic state of the mother upon the somatic condition of the foetus explain the action of the imagination of the mother upon the development of the product of conception. The opinion which refers the origin of birth-marks to intense mental impressions on the part of the mother is not without physiological foundation. Concurrently with the motor phenomena, stigmata[81] may become developed by vascular and nutritive troubles produced under the influence of a strong excitation or by the imagination.

Spitzka,[82] who approached maternal impressions from an actively sceptical standpoint, had his scepticism shaken by specimens (preserved in the British Museum) of newly hatched chicks, all of which had a curved beak like a parrot, and the toes set back as in that bird. According to the report of the curator the hens in the farmyard where these monstrosities were hatched had been frightened by a parrot which, having escaped, fluttered among them some time before the eggs were laid and greatly frightened those from whom the malformed chicks were received. It is certain that the chief argument of those who deny that maternal impressions are transmitted is defeated by this case. They have usually a.s.serted that the explanation of the nature and cause of a birth-mark was always an after-thought on the part of the mother. But there was no after-thought in this case. The hens did not publish a theory as to the malformation of their chicks. It was their owner, a gentleman of intelligence and culture, who observed the casual occurrence, and who verified the almost photographic truthfulness of the germ monstrosity by depositing it in a museum as a permanent record at which none may cavil.

Since then, the singular freaks attributable to maternal impressions of women, seen by Spitzka, have become so numerous that he has been compelled to negative the argument that they were merely accidental coincidences. He has never seen an idiotic, malformed child or one afflicted with morbid impulses derived from healthy parents free from hereditary taint in which a maternal impression could not be traced.

In a large number a direct correspondence between the maternal impression and the nature of the deformity or peculiarity could be discovered. He reports the case of a woman, about five months pregnant, who, while standing in her yard, saw her husband stab into the belly of a goat he had slaughtered. The sight of the suddenly protruding visceral ma.s.s, which happened to be imperfectly bilobar, shocked her extremely, and, starting back, she, in her great revulsion, feeling a strange sensation at the nape of the neck or back of the head, clutched the former with her right hand.

The impression continued to haunt her. When the child was born and she saw its deformity she instantly exclaimed, "Oh, the intestines of that goat!" At the back of its head the child had a large tumour of the consistency of a loose sac of a bluish colour, showing convolutions interpreted by the mother as a reproduction of the intestinal convolutions that had so shocked her. In reality they were the convolutions of a hernia containing the posterior ends of both cerebral hemispheres. The accidental resemblance of the deformity to the mental impressions was striking.

A. Lagorio[83] brought before the Chicago Medical Society several cases in which maternal impressions had produced decidedly abnormal births with deformities resembling those feared by the mother. Kiernan, in discussing these, pointed out that all were instances of checked development. He was of opinion that moral shock, generally directed, played the chief part in maternal impressions through checking development and causing either general or local reversion. Here, as Spitzka[84] shows, the statistical method can be applied. It has been long known that profound grief, mental or physical shock acting on the mother, produce cerebral defect or generally arrested development in the offspring. Of 92 children born in Paris during the great siege, 1870-71, 64 had mental or physical anomalies and the remaining 28 were weakly, 21 were intellectually defective (imbecile or idiotic), and 8 showed moral or emotional insanity. These figures, furnished by Legrand du Saulle, justify the popular designation by the working men of Paris of the defective children born in 1871 as "_enfants du siege_."

After the great Chicago fire in 1871 birth-marks, deformities, and mental defects were noticed to occur among the offspring whose mothers were pregnant with them pending the exciting time during and after the conflagration.

Spitzka has seen in practice, const.i.tutionally melancholic or mentally defective children in whom no other predisposing cause could be discovered than that the mother was struggling with direct or indirect results of the financial crisis of 1873. In several of these cases the death of the father was a contributory cause of maternal depression. In Berlin the financial crisis of 1875-80 was followed by an increase in the number of idiots born. Lombroso attributes a series of cases of microcephaly to profound mental impressions occurring during pregnancy. To the same cla.s.s of cases belong the hermaphrodites born by mothers who have been frightened in their first pregnancy and who continue to bear hermaphrodites. The continual and not ill-founded dread that the succeeding children may resemble the first is to be regarded as a contributory cause. Observers who have had a large experience with illegitimate births believe that the mental agony suffered by the unfortunate mother reacts upon the foetus, causing arrest of development, and thus accounting for the frequent occurrence of idiocy in illegitimate children.

The influence of maternal diet on the foetus is excellently ill.u.s.trated in the results of the "fruit diet" advised by certain vegetarians. Here the children[85] become, as Elise Berwig has recently shown, rickety, irritable, peevish, liable to convulsions, morally peculiar, and otherwise defective in contrast with children born of the same parents without "fruit diet" during pregnancy.

Kiernan,[86] after citing instances reported by Amabile, Carson, F. B.

Earle, Erlenmeyer, F. H. Hubbard, C. H. Hughes, Mattison, and others, of congenital opium habit where opium was needed to preserve the infant during the first months of life, states that inheritance of the opium habit seems at first an isolated phenomenon, but zoologists have pointed out that pigeons whose ancestors were fed on poppies became intractable to opium. Murrell found that the same was relatively true in England of persons descended from Bedfordshire ancestors who used infusions of poppies as a prophylactic against malaria. Nervous diseases were, however, relatively prevalent in these districts. Narcotic habits in the ancestors produces descendants in whom the normal checks on excessive nervous action are removed, so that paranoiacs, periodical lunatics, epileptics, hysterics, congenital criminals, congenital paupers, or other degenerates result. This influence is most strongly exerted when the maternal ancestor is the one affected, for to her is committed the development of the ovum prior to conception and of the child subsequently. If either is interfered with by a habit, a being defective in some respects is the result. The direct inheritance of the opium habit has been shown experimentally by Levenstein, who found by experiments on pregnant dogs and rabbits that the use of opium during pregnancy produced either abortion or still-births, or rapidly dying offspring.

In a similar manner Rennert[87] has shown that lead-poisoning occurring in the mother is apt to produce macrocephalism with frequent idiocy in the child.

This brings the observer face to face with the problem of morbid heredity.