144 THE EVOLUTION OF CONTINUITY 



environment could be " transmitted to the next generation 

 even though that generation was brought up under the 

 normal conditions of life." 



Two explanations of how this could come about are 

 mentioned by Prince Kropotkin as coming from Professor 

 Plate : " It may be that the modification of the body cells 

 was transmitted to the germ cells ; and it may be also, as 

 Weismann suggested, that we have here a case of direct 

 action of the abnormal temperature upon the germ cells." 

 Our own conclusion is that neither of these suggestions hits 

 the truth. As will be gathered from what we have already 

 suggested, our view is that as the modifying force must act 

 during development in order to impose acquired variations, 

 or must act on a developing mass of cells whose destinies 

 are diverging — in the one case to somatic fixity, in the 

 other to reproductive finality — there is what we might call 

 a parallel evolution of variation from the point of applica- 

 tion of the force. In the one case we get the recognisable 

 variation of the somatic tissue ; in the other there must be the 

 unrecognisable variation of the independent sexual element. 

 These two forms of variation must be quite different, but 

 when it is remembered that when the sexual element com- 

 bines with another to evolve a new Individual the growth- 

 cycle is repeated, and the evolution of somatic tissues occurs 

 again on the same fundamental lines, we can see how, 

 certain things being given, the somatic variations can re- 

 appear in the offspring. The fixed tissue cell belongs to 

 one cell-species, the sexual element to another ; the evolu- 

 tion of the former is on a divergent line, while that of the 

 latter is on a cycle-path which ends in return to the start. 



The fertilised ovum we have regarded as the " primordial 

 type " from which evolves the Individual on main and side- 

 lines, and the latter begin to branch out after the first few 

 division acts, as may be gathered from the Amphioxus 

 experiments mentioned on page 132. For if the first two 

 cells produced by cleavage be separated, each can develop 

 into a complete fish, though of half the normal size ; while 

 the separation of the first four cells can likewise give rise to 

 four complete fishes, each, however, of one-fourth the normal 

 size. But the first eight cells are unable to develop inde- 



