II.] GERM -PLASM NOT LOCALIZED IN PLANTS. 73 



leaves, and shoot -axes * * * may grow out under 

 favorable conditions, become rooted, form new shoots, 

 and give rise to an independent living plant." Weis- 

 mann meets this statement as follows: "Since such plants 

 produce germ -eel Is at a later period, we have here a case 

 which requires the assumption that all or nearly all cells 

 must contain germ -plasm." I do not understand the 

 significence of the phrase "such plants." The mosses 

 are no exceptions, for all higher plants develop their 

 germ -cells "at a later period." All plants are perfectly 

 sexless or somatic for a longer or shorter period after 

 germination, — that is, until they bloom. This somatic 

 stage extends over several years in many trees. In all 

 higher plants, therefore, the germ-plasm must be devel- 

 oped from the soma -plasm; and since any part of the 

 plant may, upon occasion, develop sexual organs and 

 germ -plasm, it follows that the germ -plasm cannot be 

 localized in any part of maiden plant -body. Every 

 plant possesses the same power of making new individ- 

 uals from "roots, leaves and shoot-axes" which Sachs 

 ascribes to the mosses. If, therefore, Weismann admits 

 the association of germ -plasm with the soma -plasm in 

 "all or nearly all cells" of moss, he thereby admits it 

 for all plants. It is pertinent to call attention, also, to 

 the fact that recent morphological studies have demon- 

 strated that all plants — except certain low or specialized 

 forms — undergo an alternation of generations (see Essay 

 I. and the foot-note on page 66), one generation being 

 sexual or gametophytic in office and the other sexless or 

 sporophytic. The sporophytic generation is "the plant" 

 in ferns and the flowering -plants, the gametophytic gen- 

 eration perishing as soon as the sporophyte has been 

 developed to the point of supporting itself. Another 



