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materially to the strength of the temperance movement by the introduction of eugenic arguments. Eugenists as individuals should play their part in the promotion of temperance, but eugenical societies would do well to confine their efforts in this matter to the encouragement of scientific investigations concerning racial poisons and to the promotion of such temperance reforms as have an obvious bearing on racial questions.

Amongst the list of racial poisons, malaria, arsenic, tobacco and lead have at times been included; but, except as regards lead, the evidence forthcoming has been of the feeblest. No doubt in all these cases, as in the case of alcohol, the belief in the racial effects of these 'poisons arose from the obvious damage done by them to the persons primarily affected; but the experiments until lately most often quoted to prove that alcohol is a danger to posterity do not support this form of argument; for the guineapigs treated, though intoxicated every weekday for nearly the whole of their lives, showed little or no visible signs of injury, external or internal. It is certainly conceivable that racial poisons may exist which produce no immediate harmful effects; and if the existence of any such substances should ever be conclusively established, the eugenist would probably have to lead the attack against them. For the present, however, this undiscovered bogey may be left out of consideration.

SUMMARY

The fate of future generations may now be affected in many ways, both for good and for evil. The passing on to the citizens of the future both of good traditions and of physical improvements, here described as environmental inheritance, and the pre-natal care of children, are subjects which will not here be discussed, immensely important though they are; one reason for this exclusion being that it is only by giving to eugenics a field to itself that it will have a chance of receiving an adequate share of public attention. As to the possibility of now improving the inherited qualities of our race in the future by safeguarding the existing population from the effects of

certain poisons and micro-organisms, venereal diseases are often cited as being the racial poisons involving most danger to humanity. Whether they are or are not true racial poisons, our social policy should be the same; for it is clearly right now to concentrate attention on the disastrous consequences immediately arising from these scourges. The purely eugenic question is, however, whether the syphilitic taint is passed on beyond the second or third generation. The transfer from the mother to her child of the living germ of this disease is by far the most probable explanation of the reappearance of congenital syphilitic symptoms; for the resemblance between syphilis and congenital syphilis is unlike the resemblance between such defects in parents and offspring as are undoubtedly passed on from the one to the other by natural inheritance. As to any indefinite deterioration of the race, whether syphilis produces any such result cannot now be confidently affirmed or denied; and such an uncertain factor should not be allowed to affect our social policy. Though the stamping out of venereal diseases would in several ways facilitate eugenic reform, yet the conduct of the campaign against them had better be left in the hands of the powerful societies now engaged in that admirable contest. As to whether or not alcohol acts as a racial poison, here also our social policy should not be affected by the issue; for our main aim should be to cope with the evils immediately arising from intemperance. The arguments ordinarily brought forward in favour of the view that the sober of the future will suffer from the alcoholism of to-day should carry but little weight. Some experiments on animals have, no doubt, been made which point to alcohol being a true racial poison; but these results, even if fully accepted, do not settle the question as regards the use of alcohol by man. No one can wish that it should be proved that alcohol acts as a racial poison or is an instrument of torture on the innocent; and as long as the arguments in favour of temperance founded on the racial effects of intoxication are in any way in doubt, they are of no use to the temperance reformer. Indeed, it is possible that alcohol has in some respects

a purifying effect on the race, though no one would dream of advocating its use on that account. Complete silence on these topics would, however, produce harmful effects by impeding the progress of reform in other directions. Eugenists should give their assistance freely in the temperance campaign, but eugenical societies would do well now to confine their efforts to scientific research and to the promotion of such reforms as would certainly tend to improve the inborn qualities of future generations.

CHAPTER VII

THE INHERITANCE OF ACQUIRED DIFFERENCES

In the last chapter it was seen that there are five methods by means of which posterity can now be injured or benefited, and it was suggested that for practical reasons it would be as well that only such of these methods as play a part in the process of evolution should be considered in a work definitely limited to eugenics. For this reason it was decided that environmental inheritance should here be left out of consideration, notwithstanding the fact that tradition may fairly be described as the most important element of civilization. As to pre-natal care, neither will that topic be discussed in this volume; the reasons for this omission, in so far as mother and child may in this way be directly benefited, being similar to those on which environmental inheritance was ruled out, whilst, in so far as it may be urged that future generations will thus also be indirectly benefited, the reasons for not discussing it here are about to be considered. Racial poisons have also been put on one side, both because the whole subject is too much surrounded with doubt to make it right that practical politics should be affected by it and for other reasons. Out of the original five methods there now only remain to be dealt with the inheritance of acquired characters or acquired differences, as I prefer to name them-and selection; these being the two main methods which have been suggested as having been operative in the evolutionary process. Both of them, therefore, come within the limits here laid down as indicating the proper boundaries of eugenic studies.

Dealing first of all with the inheritance of acquired differences in so far as it may be held to be a factor in

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evolution, the distinction between inherited and acquired differences has already been discussed in Chapter III. The question now under consideration is the natural inheritance of those characters or differences which we label as acquired'; a problem which may be illustrated in the following manner. Assuming the existence of a pair of twin brothers absolutely identical at birth, one of them becoming a blacksmith and the other a schoolmaster, the effects of the difference in the demands made on these two men would be that the one would become more muscular and the other more capable of assimilating new information or more able to extend the boundaries of his existing fields of knowledge. These differences having become well marked before marriage, the question at issue is whether the children of the two brothers would as a rule exhibit differences similar in kind, though not necessarily in degree, to those which differentiated their parents, the blacksmith having more muscular children and the schoolmaster offspring more educable in certain respects. When trades or callings run in families we are not surprised to find that fathers and sons both differ somewhat similarly from the rest of the community; but would any of the distinguishing marks of their fathers' callings be visible in the children of the blacksmith and of the schoolmaster if they had been brought up in exactly the same surroundings to follow some other trade? The question at issue is not merely whether the children of the blacksmith and the schoolmaster would differ in mind and body but whether the differences between them would correspond in kind with those which had arisen between their parents as a direct consequence of the differences in their occupations. If any such differences between the children could be detected, we should in these hypothetical conditions be right in assuming that they must have been due to natural inheritance; for they could not have been due to differences in surroundings, such being assumed not to exist. This is a simple illustration of the problem of the inheritance of acquired differences.

1 If there are elements of the mind which education finds to develop, that fact need not here concern us.