for sound government and legislation, for organisation and for social progress, and an inability to compete with more vigorous neighbours, both in the arts of peace and in those of war, the natural termination of which is social decline or even disruption. It is exceedingly questionable if any student of history will be found to maintain that there is not an iota of evidence' of the past existence of such degeneracy.

As to why the germ-plasm of different individuals should vary in susceptibility to the action of adverse factors of the environment, we know very little. It is not inconceivable, indeed it is a reasonable assumption, that its state of nutrition may be subject to change, and that this may determine its immunity or vulnerability; or the same result may be brought about by the absence or deficiency of some internal secretion. This question is one of great moment, but it is too intricate to enter upon in this place.

The fact is, then, that not only are there no a priori reasons against the modification of the germ-plasm by the environment, in spite of much reiteration to the contrary, but there are many such reasons in favour of this modification taking place. Doubtless the germmaterial possesses a considerable degree of resistance to the action of the environment; for, were it otherwise, and did it reflect every transient change, racial stability could hardly exist. But there is a great difference between some degree of resistance and absolute immunity; and, when we remember that after all the germ-plasm is still living protoplasm and consequently dependent for its sustenance upon the quantity and quality of the fluids supplied to it, the view that it can lead a charmed life, utterly uninfluenced by any condition of its host, is untenable. As Beard says, 'the germ-cell must react to and be influenced by its environment-a conclusion not only accepted by most competent biologists of the present day, but acquiesced in by Weismann himself.

However, the question is no longer one of speculation and a priori reasoning. Whatever may be asserted of the theoretical impossibility that the germ-cell should be adversely affected by its environment, there is now very clear evidence that it is so affected; and to some

of this evidence we may briefly refer. One of the earliest observations (1861) was that of Dr Constantin Paul regarding the effect of lead. This observer found that out of thirty-two pregnancies, in which the father alone suffered from lead poisoning, the mother being free from that condition, twelve of the children were stillborn, eight died during the first, four during the second, and five during the third year of life, while another died later in childhood. Similar data were published by Lizé (1862) regarding workers exposed to the fumes of nitrate of mercury. Out of twelve pregnancies in which the father alone was exposed, there were four stillbirths; of the remaining eight children, three died before the fourth year, and only one of those who survived could be described as vigorous. The toxic effects of alcohol upon growing protoplasm are well known; and, since experimentation with this is comparatively easy, it has naturally formed the subject of many investigations. One of the most recent is that by Stockard upon guinea-pigs, by which it was shown that the net result of twenty-four matings of alcoholised fathers with normal mothers was only five surviving offspring, or no more than might have been expected from a single pairing of two healthy animals; and, further, that at the age of two months these five survivors were only half the usual size. Dr E. Bertholet, after a series of microscopical examinations in 120 alcoholic and non-alcoholic human beings, was able to demonstrate very clear differences, and to assert that 'the hurtful influence of chronic alcoholism upon sexual glands is not to be denied.' Similar results have been obtained with other poisons; and during recent years it has also been shown that germ variations may be induced by temperature (Sumner, Bordage, Tower) and by the injection of chemicals into the immature ovary (Macdougal). Finally, from enquiries which I have lately made into the effect of X-rays, there seems to be no doubt that males working with unprotected tubes are rendered temporarily sterile owing to the action of the rays upon the sperm-cells. If this and other agencies can thus bring about the death of the germ-cell, it is a justifiable inference that smaller doses can so injure it as to produce a living but impaired offspring; and the

earlier observations above quoted show that this is actually the case.

In view of the evidence which is now available and is daily increasing, it is impossible to deny that the germ-cells may be adversely affected by the environ

As to the actual causal agents of this change in human beings our knowledge is still incomplete. My own observations lead me to think that Alcoholism, Tuberculosis, and venereal diseases play an important part. But there may be many others with which we are as yet unacquainted, and which will certainly be brought to light when once we discard the bogey of 'spontaneous variation,' and seek them in a true scientific spirit, devoid of preconceived notions as to what may be possible and what impossible.

The important question now arises as to the nature of the germinal change which is thus induced. In spite of the many researches of recent years, we still know very little about the physical basis of inheritance; but this much is certain, that, in some at present mysterious way, the germ-cell contains 'representatives' or 'determinants' of all the variable parts of the body of the offspring to which it subsequently gives rise. Perhaps the best way of regarding these is that of a series of directive forces or specific energies, each of which is concerned with directing the growth of a particular tissue. On this hypothesis we may assume that the effect of toxic agents is to reduce this innate potentiality, and to bring about what may be termed a devitalisation, or an impairment of the whole, or of certain specific, energies of the germ-cell. This will not only be operative in the case of the immediately resulting offspring, but, since it is fundamental, may involve subsequent generations. This is in no wise antagonistic to the view of germ-continuity.

But the different organs of the human body, as they exist to-day, vary greatly in what may be called their antiquity. There are some-for instance, the circulatory system-which have undergone comparatively little change with the evolution of the human race through many lower species. There are others, such as the nervous system, which have undergone a very great

elaboration, probably even in man himself. It is legitimate to conclude that the innate germinal potentiality of the systems of less antiquity, which have undergone more recent evolutionary change, will be more liable to alteration under adverse or abnormal conditions of the environment than will the potentiality of those which are more organically fixed and have, in fact, a longer heritage; and hence it will come about that these adverse factors exert a selective influence upon the constituents of the germ-cell, being chiefly operative upon the higher parts of the nervous system. At the same time our conception of development can hardly be that of a series of organs each pursuing its own growth independently. It seems likely that a certain mutual inter-restraint exists, and that, where the potentiality for growth of one organ or tissue is rendered defective, the lessening of restraint may result in irregularity and overgrowth of contiguous tissues, with the production of gross anatomical anomalies and developmental errors.

When we turn to the manifestations of degeneracythat is, to the manner in which these pathological variations of the germ-cell are revealed in the offspring-we find strong corroboration of these views. Retrogressive variations, manifested generation after generation, are to be found, it is true, in many organs, such as the skin, the eyes, the skeleton, etc.; but the commonest expression of all and by far the most frequent form of degeneracy is seen in a defective and abnormal constitution of the higher parts of the nervous system, that is, in the parts concerned with the functions of mind. The usual medical term for this manifestation of degeneracy is neuropathic diathesis'; and its physical basis is undoubtedly, as has now been shown by many exhaustive enquiries, an impairment of neuronic potentiality which is germinal in origin and may be transmitted generation after generation.

The manifestations of this neuropathic diathesis vary greatly in their degree and nature. In the slighter forms of impairment, as already remarked, there is simply a lessened durability and diminished power of resisting the stresses and strains of life; a weakening of nerve vigour, a proneness to psychasthenia, and a consequent inability for sustained competition. If more pronounced,

there is a tendency to early mental dissolution or dementia, to hysteria, epilepsy, insanity and other marked psychopathic disorders; while, if still more marked, there are grave defects of anatomical development, resulting in feeble-mindedness, imbecility, or idiocy. It has now been conclusively shown that, while some stocks evince no tendency to any of these abnormal mental states, there are others in which such conditions occur with great frequency for many generations. Some members of such a stock may be epileptic, others suffer from insanity or marked moral failing, while others may be feeble-minded or even idiots. Since the environment of such persons differs in no material particular from that of the mentally healthy section of the community amongst whom they live, it is clear that the failing is of the germ-cell and is inherited. In many family histories it is possible to trace a definite progressive accentuation of the impairment, and in some even to trace it to its origin. Thus, in persons suffering from the mildest manifestations, neuropathic antecedents are relatively uncommon; but a history of ancestral alcoholism or tuberculosis is frequently found. Amongst epileptics, evidence of the neuropathic diathesis occurs in about 35 per cent. of cases; in the insane this proportion reaches from 50 to 60 per cent.; while in the mentally defective it occurs in from 80 to 90 per cent. There is thus an increasing degeneracy, which reaches its culminating point in that condition in which mind has become so reduced as hardly to have an existencenamely, profound or absolute idiocy.

It has sometimes been objected that, since the particular defect of the individual is not identical with that which has existed in his ancestors, it cannot be regarded as hereditary.' This, however, is either mere hairsplitting or betokens a complete ignorance of the nature of the inheritance underlying these morbid conditions. Of course idiocy, insanity, epilepsy, etc., are no more inherited, as such, than any other human quality or defect. Inheritance consists, not in the transmission of actual qualities as we see them, but in the potentiality to develope those qualities under an appropriate stimulus. Similarly in degeneracy, what is transmitted is not epilepsy, insanity or mental defect, but a diminished developmental