The present work is the result of more than twenty years’ labour in a limited medical department of biology. It demonstrates once more the truth of the scientific principle, that the truth or falsity of any theory or working hypothesis becomes more and more demonstrable the further its application is attempted in the explanation of new lines of facts. The truth of the degeneracy doctrine had forced itself on the writer long before its popular apotheosis under Lombroso and Nordau, because it alon

Introduction Considered as a condition hurtful to the type, the conception of degeneracy may be said to appear even in the precursors of man, since animals destroy soon after birth offspring which, to them, appear peculiar. With that stage of development of the religious sense marked by assigning malign occult powers to natural objects and forces, this view of degeneracy became systematised, and exposed weakly or deformed offspring, charged to evil powers, to death. This occult conception of deg

The Stigmata of Degeneracy The attempt made by Morel to limit the doctrine of degeneracy to the domain of the morbid proved impossible, because of the rapid accumulation of data by his own school, which demonstrated that atavistic deformity played a larger part in the production of diseases. Bland Sutton does not too forcibly put this result when he states [59] that if it be difficult to define disease when restricted to the human family, it becomes obviously more difficult when disease is inves

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

Consanguineous and Neurotic Intermarriage Byron has sung [109] of the old popular belief in the advantages of cross-breeding, which arose originally in the practice of exogamy (marriage outside the tribe), or, more often, outside those having the same totem, or coat-of-arms. In all probability casual observation of deformities after intermarriage enforced the prohibition which arose after the killing of female children had led to exogamy. Totemic relationship was often far from being consanguine

Intermixture of Races Defoe, in his Trueborn Englishman , outlines a factor of great importance in degeneracy. [133] Race intermixture is much more common than is generally believed, owing to that ethnologic error consequent on the discovery of Sanscrit, which tests race by speech. Keane [134] excellently explodes this error by the following table: Profoundly mixed as this table indicates European races to be, it is far from representing the full extent of race mingling. The primitive worship of

Toxic Agents The toxic agents which influence the race toward degeneracy, exert that deterioration in a mode which closely resembles that of the degenerative powers of the acute and chronic contagions and infections. The acute poisonings by these toxic agencies resemble the acute, nervous and other exhaustion caused by the toxin of the germs underlying the infections and contagions. The chronic conditions due to these toxic agents agree in many respects with the chronic states produced by the in

Contagious and Infectious Disease Among the gains of human advance in evolution stand out prominently complete immunity from certain diseases due to germs, and partial immunity from others, which last immunity results in chronic types, rather than in acute, because of increased vital resistance in man. Tuberculosis and dourine, acute diseases in the cow and horse, have become chronic diseases, tuberculosis (or consumption) and syphilis, in man. Such chronicity is evidence of advance, yet it cons

Climate, Soil, and Food Among the factors constituting environment few have impressed the biologist so much as climate, soil, and food. The seeming modifications produced by these have made a very decided impression on the sceptical Weismann, who stated that “the possibility is not to be rejected that influences continued for a long time, that is, for generations, such as temperature, climate, kind of nourishment, &c., which may affect the germ plasm, as well as any other part of the org

School Strain Like all factors of degeneracy, school strain evinces itself in a systemic nervous exhaustion manifest along lines of least resistance, as in the neuroses of Christopher. The first types of his neuroses are due to overstrain of certain territories related with memory, as contrasted with diminished use of the association fibres connecting these. As Schopenhauer has excellently observed, man is one-third intellect and two-thirds will, and much of this last two-thirds is the result of

The Degenerate Cranium The cranium or skull is a development in part of the vertebræ or bones forming the backbone, and in part of dermal or membranous bones, which of old in reptiles, as in the alligator to-day, formed the protective armour of the skin of the head. As the head end of the spinal cord of the lancelet developed, the cartilage enclosing it developed to protect it. This was the earlier evolution. Later, another skull developed in connection with this. The cranium or skull therefore

The Degenerate Face and Nose The development of the face depends, as I have already shown, upon the enlargement and fusion of the mouth and nose cavities, and upon the later partial separation of the nose and mouth and the nose cavities, leaving the posterior nose open. It depends further upon the growth and specialisation of the face region, of which the elongation is the most prominent indication, and finally upon the development of a prominent external nose. The relations of face to cranium i

Degeneracy of the Lip, Palate, Eye, and Ear Each part or sense organ may, independently of the face as a whole, exhibit signs of degeneracy. The palate, lip, nose, eye, and ear have their own expressions of degeneracy. The palate, so far as the joining of its two parts is concerned, resists degeneracy to a remarkable degree. The cleft, which results from non-union, is usually an expression of general degeneracy acted on by its nutritive expression, albeit cleft-palate may be associated with the

The Degenerate Teeth and Jaws Next to the ears, the jaws and teeth (as was to be expected from the variability of these organs in allied animals) are most affected by degeneracy. This is particularly true of the vertebrates, especially mammals, as might have been anticipated from their phylogeny. At the head of the vertebrates is man; at the foot is the lancelet (amphioxus), which is perhaps most akin to those semi-vertebrates the ascidians, who, in their larval phase, are higher than when adult

Degeneracy of the Body As degeneracy checks the natural course of embryonic development it necessarily finds expression in the body as well as in the skull. One most striking condition is that by which development of the bones enclosing the spinal cord is checked. The spinal cord is at first essentially a notochord as in the lowest types of vertebrates. The structures surrounding the cord are not divided into vertebræ. This condition is permanent in the lancelet. Around the notochord is later fo

Degeneracy in Reversional Tendencies The hair of the head and body may never develop from the condition of down (lanugo) present in the new-born. The hair over the sexual organs may alone remain in this condition, not showing itself at puberty. In women the hair may be unusually developed on the face and chest. It may also cover the whole body, a condition which is normal in the Ainus of Japan. It may develop, as already shown, very markedly in the lumbar regions. Speech may be markedly disturbe

Degeneracy of the Brain One illustration, and a very striking one, of the influence of degeneracy on the brain is the durencephalous child which so often appears in degenerate families. Here the cerebral hemispheres and everything but the medulla and pons may be absent, while the rest of the body is in a comparatively normal state of development. Starting with such an extreme expression of degeneracy in the brain, a wide but closely linked range of deficiencies may be found in the brain of degen

Degeneracy of Mentality and Morality In the mental and moral degeneracies there is a complete transition from the durencephalic monster through the microcephalus, the idiot, the imbecile, and the feeble-minded to the mentally normal individual. Between the feeble-minded and the normal individual occurs a group whose general characteristics is, as was pointed out by Magnan, a disharmony and lack of equilibrium, not only between the intellectual operations, properly so-called on the one hand, and

Conclusions Since, as Weismann [263] admits, interference with the nutrition of the germ plasm will result in the production of variations, the fact is evident that even according to the Weismannian principle the nutrition of the parents will determine the power of the embryo to pass through the various embryonic stages up to the developed child. Impairment of nutrition may check this development at any standpoint, and may thus produce any or all of the defects due to degeneracy. Weismann has no