172 THE GERM-PLASM 



of the bud, as occurs in the Polyzoa for instance, and also even 

 the co-operation of three germinal layers in the formation of the 

 bud. 



It seems to me to be improbable that the phylogeny of gem- 

 mation in animals has taken place in the reverse manner. We 

 might assume that in the lowest Metazoa, which no longer exist 

 at the present day, all or many of the cells also contained germ- 

 plasm proper, just as in the case of the lower multicellular 

 plants. Under certain circumstances a perfect animal might 

 have been produced from each of these cells. But this assump- 

 tion would only suffice as long as the individual formed by bud- 

 ding was exactly similar to that arising from the egg. Even the 

 slightest difference between these would necessitate the presence 

 of special ids in the germ-plasm. For such a difference can only 

 depend on the fact that the two kinds of individuals are capable 

 of independent variation from the germ onwards. We should 

 therefore have to assume further, that in the course of phylogeny 

 the germ-plasm of these somatic cells from which the buds orig- 

 inated became doubled in the earlier stages of ontogeny, and that 

 it was consequently present in the germ-plasm of the egg-cell in 

 the form of a special group of ids. But this, to say the least, is 

 a very involved assumption, and can hardly be considered very 

 probable : that which presupposes a primary doubling of the ids 

 of germ-plasm is certainly far preferable to it. The following 

 chapter will make this point still more evident. 



