WEISMANN'S THEORY OF THE GERMPLASM 27 



into the determinants which control the course of 

 the ontogeny, and decide the final characters of 

 the cells. Another set of ids remains undisin- 

 tegrated, with their determinants fast bound 

 together, and, in the cell divisions, is not broken 

 up into dissimilar groups. The first set of ids is 

 the active, disintegrating germplasm ; the second set 

 is a passive, latent germplasm, which may be de- 

 scribed as accessory germplasm (NebenJceimplasma). 

 The active ids are his explanation of the embryonic 

 events, which they direct ; the accessory germ- 

 plasm is reserved to form the germ-cells, and, in 

 fast-bound condition, is handed on through a short 

 or long series of cell-divisions alongside the active 

 germplasm. Handed on in this passive state, it 

 finally reaches a group of cells which may be many 

 or few generations distant from the original egg- 

 cell, and impresses upon them the character of 

 sexual cells. This transfer of germplasm from the 

 egg to the sexual cell occurs in orderly fashion, 

 along prescribed series of cells which Weismann 

 has called the germ-tracks. Only these cells, which 

 contain part of the perfect, undisintegrated germ- 

 plasm, serve for the preservation of the species and 

 are immortal ; the other cells, since, from the dis- 

 integration due to differentiating division, they 

 contain only fragments of the perfect plasm (groups 

 of determinants or single determinants) , are mortal, 

 somatic cells. 



The formation of buds is explained in much the 

 same way as the origin of germ -cells. There is 

 handed along from the egg, through prescribed 



