A HISTORY OF SCIENCE . 



has made a second bisection, thus reaching the four- 

 cell stage, when four completely formed individuals 

 emerge from the dismembered egg. And in the case 

 of certain medusae, success has attended experiments 

 made at the eight-cell and even at the sixteen-cell stage 

 of development, the creature which had got thus far on 

 its career in single blessedness becoming eight or six- 

 teen individuals at the wave of the enchanted wand 

 that is to say, the dissec ting-needle of the biologist. 

 All of which savors of conjury, but is really only 

 matter - of - fact biological experiment experiment, 

 however, of which the implications by no means con- 

 fine themselves to matters of fact biological. For 

 clearly the fact that the separated egg-cells grow into 

 complete individuals shows that Weismann's theory, 

 according to which one of the cells contained only body 

 plasm, the other only germ plasm, is quite untenable. 

 Thus the theory of the non-transmissibility of acquired 

 characters is deprived of its supposed anatomical sup- 

 port and left quite in the air, to the imminent peril of 

 a school of sociologists who had built thereon new theo- 

 ries of human progress. Also the question of the mul- 

 tiplied personalities clearly extends far beyond the 

 field of the biologist, and must be turned over to the 

 consideration of the psychologist if, indeed, it does 

 not fall rather within the scope of the moralist. 



But though it thus often chances that the biologist, 

 while gazing stoically through his microscope, may dis- 

 cover things in his microcosm that bear very closely 

 upon the practical interests of the most unscientific 

 members of the human family, it would be a mistake 

 to suppose that it is this class of facts that the worker 



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