1 68 THE GERM-PLASM 



different groups of determinants, these eventually completing 

 one another, and interacting in such a manner that a fully- 

 formed person must result. 



4. The Phylogenv of the Process of Multiplication 



BY Gemmation 



In all probability the phylogeny of gemmation has taken place 

 along different lines. The process most likely arose independ- 

 ently in animals and in plants, and perhaps even in different 

 groups of animals it has had a different origin. 



In many of the lower plants, the cells and organs of which 

 are only slightly differentiated, all, or at any rate many, of the 

 cells can individually give rise to a new plant under certain cir- 

 cumstances. In such cases we might be inclined to suppose that 

 each cell contained originally, i.e. at the time of its phyletic 

 origin, the entire mass of determinants of the species, or, in other 

 words, contained germ-plasm. The various differentiations of 

 the cells on the upper and lower surfaces, for instance, would 

 consequently depend on the different determinants becoming 

 active in response to different external stimuli : some, for in- 

 stance, might be stimulated by a bright light, and others by a 

 dim light. 



This explanation would hardly suffice in the case of the higher 

 plants, the differentiation of which is far too complicated to be 

 due to the effect of external causes. A large number of the 

 cells must nevertheless contain germ-plasm, which, however, is 

 in the unalterable (* gebundenen ') state, — that is to say, it is 

 not merely inactive, but is incapable at the time of undergoing 

 disintegration. This stage in the phylogeny of gemmation may 

 be derived from the earliest stage. As the plant underwent an 

 increasing differentiation, cells appeared which only contained 

 special determinants, in addition to those with germ-plasm 

 proper ; and this may have led to the condition which we now 

 find in the highest plants, and which is distinguished by the 

 fact that many cells only contain specific determinants, while a 

 large number of others possess in addition germ-plasm in the 

 unalterable condition, which only becomes active under certain 

 influences. I shall have occasion to return to this subject 

 later on. 



In the case, again, of the various groups of the lower animals 



