HEREDITY.

Dominion, Volume 6, Issue 1687, 1 March 1913, Page 18

HEREDITY.

THE OTHER SIDE OF THE PROBLEM.

INTERESTING ADDRESS BY PROF.,J. A. THOMSON. A scientific knowledge of the faotors of life lias grown'. £0 rapidly of recent years, that there has been a natural tendency to over-emphasise, and to "take sides" unnecessarily. Tho object of Professor J; Arthur. Thomson's recent address at the Holborn Hall, London, delivered in connection with tho National Council of Public Morals, was to plead for a more careful consideration of tho influence of surroundings and habits of life, which recent research, most valuable up to its limits, has tended to depreciate unduly, perhaps even dangerously. AVhen wo iiiquiro into the horoscope of any organism we find that there are three factors or fates which determine what kind of organism it is going to bfi. Tho first is heredity, tho organic relation between successive generations, and that, of course, is fundamentally important. Tile second is "nurture"—all manner of surrounding influences that play upon' tho organism and that tile organism plays with. Tile third is the cosmic faotor of chaneo, or providence, which offers or withholds opportunities. The hereditary factor is fundamental. Our start in lifo is rigorously determined by our lineage. As Heine said, a man cannot bo too careful in the choice of his parents. The impression which the study of' the facts of inheritance leaves in tho mind is unquestionably fatalistic. Yet it must bo remembered tlmt the hereditary nature cannot be realised or developed without approprihte nurture. Raw Materials of Progress. Tho hereditary relation tends on the wholo to persistence of resemblance, to racial inertia. Life tends to beget like. But while heredity limits variability it also affords jt opportunity; and it secures that a germinal variation gets its chance of proving its "survival-value in the struggle for existence. Many variations are liko suppressions or exaggerations of already existing hereditary items. But others aro like new departures, qualitative, not quantative. Probably tho=.e furnish tho most important raw materials of progress. In mankind tliev spell genius, originality, individuality, idiosyncrasy, and so on—in short, a new pattern. Now, ..while wo cannot give any recipe for genius,,- there are two interesting points to bo noted. First, that experimental zoology has disclose;! the importanco of . changed environment as a variational stimulus. Secondly, it seems plain. that an advantageous new departure may fail of its promise if it be .not associated with an appropriate amelioration of nurture. Thero is reason to ljelievo that some misunderstanding has arisen through taking ■ too simple a view of tho relation between tho organism and its environment. Tho relation is multiple, not: single. There* /is the relation of essential dependence, for an organism cannot live in vacuo; there is tho relation of appropriate stimulation, for tho environment is needed as a trigger-puller in development; there is- the relation of transient' adjustment between the plastic organism and its. surroundings; there is the relation of permanent . modification, when tho creature receives lasting dints or "acquired characters" from its surroundings; there is tho relation of variational stimulus, when a chango in nurture saturates through the body and prompts the 'gcrni-plasin to vary; and there are other relations. Perhaps those who have depreciated the importance of nurture have not done jus- ' tico to the manifold rolo which it fills in relation to the organism. Importance of Nurture. Everyone knows that. changes of nurture produce individual modifications or acquired characters, and when they aro re-impressed generation after generation it is almost as if they were inherited, they may be of indirect importanco for' tho race, serving as life-saving screens until germinal variations in tho same direction have had tiinci to grow strong, but they are not of much direct importance since there is very little evidence that they are ever transmitted. There is no likelihood that we shall ever return to the crude belief in the inheritance of acqmred characters. Indeed, Weismann gave this its death-blow. But nurture does not ceaso to be important thou»li its direct results are not entailed. It Incomes for practical purposes all the more important to control the nurture of each successive generation. Moreover, quite a number of recent researches have civen a new aspect to the problem by showing if they are rightly interpreted, that lon»conturned and deeply saturating nurtural influences may affect the germ-plasm, and thus the race, in a quite definite, and soecific way. Thus we return to the importance of the environment on a higher turn of the spiral. „°, f cflicie »cy is, indeed, inborn mo-f of ?!! ' makin * tm • ] ,as !f dfi Pcnds on the nurture. Tho inheritance is the seed-corn-nurture is the soil and the sunshine ami tho ram. IVurturo cannot create, but"it can hinder or favour development. One cannot make a silk purse out of a sow's ear but inheritance without appropriate nurture remains liko the talent hkl in a napkin and buried in the ground As ago: " What y° l < have in! herited from your ancestors, exercise if ~S<3 A ml .] s become your verv own. ( Thus if the importanco of hereditary nature is fundamental, tho importance of "nurt.uro"-wMch is "the other sido of hoTedity"—is supreme.