Septembee 25, 1908] 



SCIENCE 



389 



of the race. According to Weismann, 

 there is precisely the same bar to the in- 

 heritance of somatic change. 



The racial or phyletic life of all organ- 

 isms is conceived by him as a series of 

 germ-cells whose activity is limited to 

 varying, and whose survival in any gen- 

 eration depends on the production of a 

 successful soma or body capable of hous- 

 ing, protecting, and feeding the germ- 

 cell. Most people would a priori declare 

 that a community where experience and 

 action are separated must fail. But the 

 bee's nest, which must be allowed to be 

 something more than an illustration of 

 Weismann's theory, proves the contrary. 



It is clear that there must be war to the 

 knife between the theory of Weismann and 

 that of the somatists — to coin a name for 

 those who believe in the inheritance of ac- 

 quired characters. A few illustrations 

 may be given of the strength of Weis- 

 mann's position. Some trick or trivial 

 habit appears in two successive genera- 

 tions, and the son is said to inherit it from 

 his father. But this is not necessarily a 

 case of somatic inheritance, since accord- 

 ing to Weismann the germ-plasm of both 

 father and son contained the potentiality 

 of the habit in question. If we keep con- 

 stantly in view Weismann's theory of con- 

 tinuity, the facts which are supposed to 

 prove somatic inheritance cease to be de- 

 cisive. 



Weismann has also shown by means of 

 his hypothesis of "simultaneous stimula- 

 tion"^ the unconvincingness of a certain 

 type of experiment. Thus Fischer showed 

 that when chrysalids of Arctia caja are 

 subjected to low temperature a certain 

 number of them produce dark-colored in- 

 sects; and further that these moths mated 

 together yield dark-colored offspring. 



' I borrow this convenient expression from 

 Plate's excellent book, " Ueber die Bedeutung des 

 Darwin'sclien Seleetionsprincips," 1903, p. 81. 



This has been held to prove somatic in- 

 heritance, but Weismann points out that 

 it is explicable by the low temperature 

 having an identical effect on the color-de- 

 terminants existing in the wing-rudiments 

 of the pupa, and on the same determinants 

 occurring in the germ-cells. 



It does not seem to me worth while to go 

 in detail into the evidence by which 

 somatists strive to prove their point, be- 

 cause I do not know of any facts which are 

 really decisive. That is to say, that 

 though they are explicable as due to 

 somatic inheritance, they never seem to 

 me absolutely inexplicable on Weismann's 

 hypothesis. But, as already pointed out, 

 it is not necessary to look for special facts 

 and experiments, since if the mnemic 

 theory of ontogeny is accepted the devel- 

 opment of every organism in the world 

 depends on somatic inheritance. 



I fully acknowledge the strength of 

 Weismann's position; I acknowledge also 

 most fully that it requires a stronger man 

 than myself to meet that trained and well- 

 tried fighter. Nevertheless, I shall ven- 

 ture on a few remarks. It must be re- 

 membered that, as Romanes' pointed out, 

 Weismann has greatly strengthened his 

 theory of heredity by giving up the abso- 

 lute stability and perpetual continuity of 

 germ-plasm. Germ-plasm is no longer 

 that mysterious entity, immortal and self- 

 contained, which used to suggest a physi- 

 cal soul. It is no longer the aristocrat it 

 was when its only activity was dependent 

 on its protozoan ancestors, when it reigned 

 absolutely aloof from its contemporary 

 subjects. The germ-plasm theory of to- 

 day is liberalized, though it is not so 

 democratic as its brother sovereign pan- 

 genesis, who reigns, or used to reign, by an 

 elaborate system of proportional repre- 

 sentation. But in spite of the skill and 



° " An Examination of Weismann," 1893, pp. 

 169, 170. 



