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PENGE PUBLIC LIBRARY.

Art. 3.-HEREDITY AND ENVIRONMENT IN REGARD TO SOCIAL REFORM.

1. Heredity. By J. A. Thomson. London: Murray, 1908. 2. The Laws of Heredity. By G. Archdall Reid. London : Methuen, 1910.

3. Disorders of Post-Natal Growth and Development. By Hastings Gilford. London: Adlard, 1911.

4. Outlines of Evolutionary Biology. By Arthur Dendy. London: Constable, 1912.

5. Descendants of Immigrants. By Franz Boas. London: Frowde, 1913.

6. Problems of Life and Reproduction.

(Progressive Science Series.) By Marcus Hartog. London: Murray, 1913.

And other works.

It will be generally admitted that the efficiency of a nation depends at the bottom, not upon the nature of its laws, religion, and social institutions, but upon the condition of its people. No doubt there is a correlation between the two; sooner or later the one inevitably tends to react upon the other; but it is the condition of the people which is the primary and essential factor in national progress or decadence. This being the case, the function of the State must be to secure the highest possible mental and physical development of the mass of its citizens; and this must be the objective of all true social reform.

The factors concerned in this development are numerous and varied, but all of them may be referred to one of two groups. They are either intrinsic or extrinsic, that is, due to heredity or environment; and it is the relative influence of these in the development of the individual and the well-being of the community which it is proposed to consider. Such a consideration seems not inopportune, because it is a subject on which widely divergent views are maintained, and even professional biologists are divided into two distinct schools regarding the effects of heredity and environment upon the course of evolution. More than a hundred years ago (in 1809) Lamarck propounded the view that the offspring might start life from a higher developmental plane owing to the transmission of qualities acquired by its immediate

antecedents. A similar opinion was held by Charles Darwin and Herbert Spencer, the former explaining such occurrence by his 'provisional hypothesis of Pangenesis,' the latter by his theory of Biological Units.' But with the discovery of the continuity of the germ plasm, and largely as a result of the writings of August Weismann, opinion underwent a profound change. Weismann has since very materially modified his views as to the effect of the environment upon the germ plasm; but the insistence upon its immutability by such writers as Sir Ray Lankester and Dr Archdall Reid has caused it to be assumed by the laity that this immutability of the germ is now an established fact, and that variations are never due to the action of the environment, but are 'spontaneous' in origin.

This state of mind is manifest even in the Report of the Royal Commission on the Feeble-minded, which declared that, while mental defect had a strong tendency to be inherited, it was usually 'spontaneous' in origin. It is, however, quite a mistake to imagine that this view of the impossibility of the germ plasm being modified by the environment, or even of the non-transmission of acquirements, is held by all biologists. On the contrary, during the last few years there has been a distinct reaction from the elaborate theories of Weismann, as well as from the mechanical doctrine of the phenomena of life; and several valuable works have been published reaffirming the Lamarckian and vitalistic positions. One of the most recent and important is that of Prof. Marcus Hartog on 'Problems of Life and Reproduction.' In this work the author shows that the reproductive division of the cell takes place in accordance with a force which he designates 'mitokinetism,' and which differs from any physical force with which we are at present acquainted; he further shows that this cell-division is a natural provision for the removal of senescence; he discusses the whole problem of fertilisation, adduces many arguments and instances in favour of the transmission of acquired characters, and reaffirms the vitalistic as opposed to the mechanical or physico-chemical theory of life. Prof. Hartog will, no doubt, incur the odium biologicum for these opinions, but the arguments and facts brought forward are such as cannot be ignored in any honest attempt to arrive at the

true factors underlying development; and his book is exceedingly interesting as showing the existence of a band of workers, endeavouring fearlessly to seek the truth.

We find a similar divergence of opinion with regard to the methods of social reform. On the one hand, the Eugenists are supposed to hold the opinion that heredity counts for everything, and that the influence of the environment, if it exists at all, is so infinitesimal that it may be entirely ignored. On the other hand, the Environists, if I may so term them, hold the exactly opposite view. According to them, heredity is of no moment; all individuals are born with equal potentialities; and the inequalities which subsequently appear are entirely due to the surroundings. They consequently seek the remedy for all human and social defects in an improvement of the environment. It may be that such restricted views as these are only held by the most extreme protagonists of either school; nevertheless they mark two distinct lines of thought which are very apparent in propaganda and suggested policy, and they serve as a convenient standpoint from which the question may be discussed.

Now even a casual acquaintance with the facts of everyday life should be sufficient to show the falsity of such extreme ideas. It is obvious that both heredity and environment, nature and nurture, must play a part in the production of each individual. Indeed, when the matter is considered closely, the connexion between them is seen to be much more intimate than is commonly supposed, and it is by no means easy to say where the one begins and the other ends. The rôle of the germ plasm, which constitutes the organic link between successive generations, is not to transmit organs and tissues already laid down in miniature, as was formerly thought, but merely to hand on certain potentialities of development. Before these potentialities can be realised some kind of milieu is clearly essential; and hence environment must be concerned in, and a condition of, all development. On the other hand, even if it could be shown that the appearance of some particular quality or property of the individual was largely the result of external influences-as, for instance, the development of pigment in the epithelial cells of animals exposed to bright sunshine-it is clear

that this could never have been produced without an inherent potentiality for such development. The point to be emphasised is that the life-cycle of every individual is an incessant reaction between intrinsic tendency and extrinsic stimulus, and that his condition is necessarily dependent not on heredity or environment, but on both.

It does not follow, however, that these two factors exert an equal influence. It is possible for the inherent tendency to the development of a particular quality to be so potent that no action of the environment is specially needed for its manifestation; on the other hand, the tendency may be so slight that no condition of the environment, however favourable, suffices to call the quality into being. A familiar instance of the former occurs in the black skin of negroes born in temperate climates, and of the latter in the absence of pigment of the albino. It is, however, with such qualities as make for the efficiency or non-efficiency of society that we are particularly concerned; and the problem is to ascertain the relative parts which these two factors play in their development.

During recent years numerous attempts have been made to solve this problem; but many of them are far from satisfactory. Those who have approached the subject from the point of view of heredity have only too often ignored the possible effect of the environment; whilst those who have dealt with it from the aspect of the environment have been too prone to exclude the possible influence of heredity. Undoubtedly the researches of both Mendelians and Biometricians have led to the discovery of facts of the utmost importance; but it cannot be too strongly urged that such human qualities as 'character,' ability' and 'social efficiency' are extremely complex, and in dealing with them the greatest care is needed to ascertain all the factors involved. It is only when all these possible influences have been sifted to the bottom in each case, and a sufficiently large series of such cases collected, that the establishment of general conclusions becomes possible.

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For instance, the recurrence, generation after generation, of some particular aptitude, trait or peculiarity may be due to a marked tendency deeply ingrained in the

family; but it may also be due to the fact that each successive generation has been exposed to an environment especially favourable for its production. It is quite likely that many so-called inherited qualities, such, for example, as ability in music, art or administration, may in this way be as much influenced by early surroundings and training as by heredity. The only proof of the existence of a tendency in marked degree would be the development of the quality in spite of the environment. On the other hand, it cannot be questioned that the attempt to correlate certain individual peculiarities with certain particular factors of the environment, regardless of the possible influence of heredity, may readily give rise to most fallacious conclusions.

With regard to many anatomical conditions, the evidence is now sufficiently clear to enable fairly definite statements to be made. We know, for instance, that the general bodily conformation of man, together with certain particular deviations therefrom, are determined by heredity. With regard to the psychological attributes of mankind, however, using this term to embrace his moral, mental and social qualities, there is much more difficulty, and further research is greatly needed.

I propose first of all to deal with heredity and environment as they affect the individual, and it will be convenient to consider first stature and physical development. It is a well-known fact that stature and physique vary with race and even with nationality. The tall Patagonians, the dwarfed Fuegians, the massive Teutons, and the small Laplanders and Japanese are sufficiently familiar examples. It is possible that to some extent these differences may be induced by differ ences of climate, food and mode of life; but that they are largely hereditary is shown by the fact that they still tend to persist in individuals born and reared in foreign surroundings. Even in a mixed race like the English, living under practically identical conditions, the average stature of those of Teutonic and those of Celtic ancestry is markedly different. The influence of heredity in determining stature has, indeed, been fully demonstrated by experiments conducted on Mendelian lines.

It does not follow, however, that the environment has no effect; on the contrary, there are many reasons for

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