614 



SCIENTIFIC THOUGHT. 



variation in special instances would at least allow us to 

 accumulate many interesting life-histories of families of 

 living creatures, and might some day lead to important 

 generalisations. Mr Galton has himself made an 

 attempt to modify and further elaborate the hypothesis 

 of Pangenesis ; 1 and Mr William Bateson has given us, 



1 Mr Galton in 1871 advanced 

 certain objections to the theory 

 of Pangenesis, based upon experi- 

 ments made with the transfusion 

 of blood, and tending to show that 

 blood cannot be the carrier of the 

 germs or gemmules. See a paper 

 read before the Royal Society, 

 March 30, 1871. Darwin did not 

 think Pangenesis had " received its 

 deathblow, though from presenting 

 so many vulnerable points, its life 

 is always in jeopardy" ('Life of 

 Darwin,' vol. Hi. p. 195). In 1875 Mr 

 Galton published an article in the 

 'Contemporary Review,' vol. xxvii. 

 p. 80, entitled " A Theory of Hered- 

 ity," in which he put what may be 

 termed the atomic theory of life 

 and its propagation into a form in 

 which it might serve as a working 

 formula for statistical research. 

 It is a mistake to look upon any 

 such theory as a biological, 

 mechanical, or historical explana- 

 tion. For statistical purposes only 

 the scantiest data need be borrowed 

 from biology. There is, however, 

 one very important biological con- 

 ception which Galton introduced, 

 which is not contained in Darwin's 

 " provisional hypothesis," and which 

 somewhat later became celebrated 

 mainly through the writings of 

 Prof. Weismann. This is the dis- 

 tinction between the germ-plasma 

 and the body-plasma, the former 

 preserving the continuity of life 

 and inheritance, whereas the latter 

 forms the character of the indi- 

 vidual, and is probably sterile. In 

 fact, Galton, from a purely statis- 



tical point of view, anticipated as 

 several other naturalists did, from 

 various other aspects the theory 

 of the differentiation of the ger- 

 minal from the personal portions 

 or aggregates of life units in the 

 " stirp " or sum - total of organic 

 units of some kind which are to be 

 found in the newly fertilised ovum. 

 Prof. J. A. Thomson (' The Science 

 of Life,' p. 147) gives the following 

 succinct statement of the concep- 

 tion of "stirps": "First. Only 

 some of the germs within the stirp 

 attain development in the cells of 

 the 'body.' It is the dominant 

 germs which so develop. Second. 

 The residual germs and their pro- 

 geny form the sexual elements or 

 buds. The part of the stirp 

 developed into the ' body ' is almost 

 sterile. . . . The continuity is kept 

 up by the undeveloped residual 

 portion. Third. The direct descent 

 is not between body and body, but 

 between stirp and stirp. The stirp 

 of the child may be considered to 

 have descended directly from a 

 part of the stirps of each of its 

 parents ; but then the personal 

 structure of the child is no more 

 than an imperfect representation of 

 his own stirp, and the personal 

 structure of each of the parents is 

 no more than an imperfect repre- 

 sentation of each of their own 

 stirps. This is a definite expression 

 of the notion that the germinal cells 

 of the offspring are in direct contin- 

 uity with those of the parents. The 

 antithesis between the ' soma ' and 

 the chain of sex-cells is emphasised." 



