198 THE CONTINUITY OF THE GERM-PLASM AS THE 



persistence of the parent germ-cells in those of the offspring ; for a 

 cell the offspring of which become partly somatic and partly germ- 

 cells cannot itself have the characters of a germ-cell ; but it may 

 nevertheless contain germ-idioplasm, and may thus transfer the sub- 

 stance which forms the basis of heredity from the germ of the 

 parent to that of the offspring. 



If we are unwilling to accept this hypothesis, nothing remains 

 but to credit the idioplasm of each successive ontogenetic stage with 

 a capability of re- transformation into the first stage. Strasburger 

 accepts this view ; and he believes that the idioplasm of the nuclei 

 changes during the course of ontogeny, but returns to the condition 

 of the first stage of the germ, at its close. But the rule of pro- 

 bability is against such a suggestion. Suppose, for instance, that 

 the idioplasm of the germ-cell is characterized by ten different 

 qualities, each of which may be arranged relatively to the others in 

 two different ways, then the probability in favour of any given 



combination would be represented bv the fraction f ) = - : 



V 2' 1024 



that is to say, the re-transformation of somatic idioplasm into germ- 

 plasm will occur once in 1024 times, and it is therefore impossible 

 for such re-transformation to become the rule. It is also obvious 

 that the complex structure of the germ-plasm which potentially 

 contains, with the likeness of a faithful portrait, the whole in- 

 dividuality of the parent, cannot be represented by only ten charac- 

 ters, but that there must be an immensely greater number ; it is 

 also obvious that the possibilities of the arrangement of single 

 characters must be assumed to be much larger than two ; so that we 



/i\ 

 get the formula f 1 , where p represents the possibilities, and n the 



characters. Thus if n and p are but slightly larger than we 

 assumed above, the probabilities become so slight as to altogether 

 exclude the hypothesis of a re-transformation of somatic idioplasm 

 into germ-plasm. . 



It may be objected that such re-transformation is much more 

 probable in the case of those germ-cells which separate early 

 from the somatic cells. Nothing can in fact be urged against 

 the possibility that the idioplasm of (e. g.) the third generation of 

 cells may pass back into the condition of the idioplasm of the germ- 

 cell ; although of course the mere possibility does not prove the 



