468 THE GERM-PLASM 



nature, but also ids of germ-plasm in an unalterable condition 

 — in which they are at the time incapable of undergoing 

 disintegration — were distributed to certain cells of the body. 

 This addition of latent germ-plasm to certain series of somatic 

 cells also results in tlie formation of germ-cells in most multi- 

 cellular forms ; while the power of regeneration depends on a 

 systematic addition of certain inactive determinants, or groups 

 of determinants, to certain cells of the body. 



Further complications of the germ-plasm produce the phenom- 

 ena of alternation of generations and the polymorphism often 

 connected with it, as well as the sexual dimorphism always oc- 

 curring in a greater or a less degree in connection with ' sexual 

 reproduction.' All determinants and groups of determinants 

 which exist in two or more forms, must be present in a double 

 or multiple condition in the germ-plasm, and be so arranged 

 that each constituent part only becomes active in turn. This 

 assumption is, however, insufficient in the case of alternation 

 of generations, in which several kinds of germ-plasm must be 

 present and become active in turn. 



Thus an ever increasing complexity of the substance which 

 renders the repetition of the organism possible is gradually 

 produced in the phylogeny of living beings, and eventually 

 reaches so high a degree that it is difficult to believe that 

 such an infinite complexity of structure can actually exist in 

 particles so minute. The more deeply, however, we penetrate 

 into the phenomena of heredity, the more firmly are we con- 

 vinced that something of the kind does exist, for it is impossible 

 to explain the observed phenomena by means of much simpler 

 assumptions. We are thus reminded afresh that we have to 

 deal not only with the infinitely great, but also with the infinitely 

 small ; the idea of size is a purely relative one, and on either 

 hand extends infinity. 



