130 Plant Genetics 



and vegetative apogamy, and to the fact that in such a 

 case any theoretical scheme of factors constructed to 

 explain breeding results would be without any signifi- 

 cance. 



Again, in such a complex organism as the sporophyte 

 it is hard to say at all times just what things are being 

 inherited and what things are merely responses. Finally, 

 there always remains the confusing problem connected 

 with germ plasm and body plasm. Are these two plasms 

 as distinct in the higher plants as they seem to be in 

 animals ? In any event, can the body plasm affect the 

 germ plasm in any significant way, and is there any 

 mechanism to justify the inheritance of acquired char- 

 acters? These questions are simply samples of the 

 many complexities that confront us when dealing with 

 such organisms as the higher plants. The suggestion 

 has been made already that simpler plants be studied 

 which show fewer complexities. Algae, and even bry- 

 ophytes, have much to teach in the field of genetics, 

 for in such plants germ plasm and body plasm are not 

 clearly differentiated; frequently they are almost one 

 and the same thing. Also such a phenomenon as 

 parthenogenesis is more easily studied in such plants, for 

 the structures involved are superficial and therefore 

 easily observed and controlled. This suggests another 

 advantage, therefore, in the study of inheritance in 

 gametophytes, for in algae practically everything is 

 gametophyte, while in bryophytes the gametophyte 

 generation is the dominant one and therefore the one 

 providing the best experimental material. 



There is one disadvantage in breeding work among 

 these lower forms that should be realized, and that is 



