514 BOTANICAL GAZETTE [june 



chromosomes. This may be a rather general situation among the simpler 

 plants, where germ plasm and body plasm are merged. Whether it is at all 

 applicable to higher plants is questionable. Perhaps the " phylogenetic age" 

 of the latter has brought this difference of body plasm and germ plasm, involv- 

 ing a rigid chromosome mechanism.' The other picture is "that the swarming 

 period .... is not one of aimless movement .... but a definitely directed 

 effort to achieve for each cell a specific relation to its fellows." Successful 

 achievement means normal colonies; otherwise monstrosities result.. This 

 situation could apply only to a very limited number of cases, even among the 

 lower plants. Among higher plants a vivid imagination might attempt to 

 apply it to the free nuclear stage in the embryo formation of gymnosperms, or 

 in the organization of the embryo sac of angiosperms. The author, however, 

 does not carry his ideas beyond Pediaslrum, where they seem quite appro- 

 priate and well founded. Similarly careful work upon less peculiar types of 

 algae should yield even more profitable suggestions. — Merle C. Coulter. 



Mendelian inheritance in gametophytes. — One of the most critical tests 

 of the current theoretical mechanism for inheritance lies in the behavior of the 

 gametophyte generation in inheritance. If our Mendelian mechanism is 

 correct, gametophytes should show predictable peculiarities; segregation 

 should take place in the first hybrid generation, and dominance should be 

 out of the question. Such an investigation is not particularly hopeful among 

 angiosperms, owing to the insignificance of the gametophytes. In fact it is 

 a rather general opinion that "the characters which they possess appear to be 

 wholly sporophytic, the factors which they carry functioning only after fertiliza- 

 tion."^ Belling'' ejs^lains semi-sterility in beans on the basis of the germinal 

 equipment of the gametophytes upon the gametophytes themselves, but this 

 merely involves lethal effects. 



More hopeful material is provided by the lower plants, where the gameto- 

 phyte generation is more prominent and really has characters of its own. 

 Transeaus reports hybridization in Spirogyra, and it is significant that he can 

 give it a Mendelian interpretation. Unfortunately the work is as yet merely 

 observational rather than experimental. Hybridization was observed taking 

 place in nature between S. communis and S. varians, S. varians and S. poHicalis. 

 The 3 species involved showed distinguishing characters in the shape and 

 size of the vegetative cells, and the shape and orientation of the zygotes. The 

 auther looked in the immediate vicinity, therefore, for possible hybrids result- 

 ing from these crosses which should display new combinations of the parental 



3 East, E. M., and Park, J. B., Studies on self-sterility. I. The behavior of 

 self-sterile plants. Genetics 2:525-609. 191 7. 



'^ Belling, John, Lethal factors and sterility. Jour. Heredity 9:161-165. 1918. 



s Transeau, Edgar Nelson, Hybrids among species of Spirogyra. Amer. Nat. 

 53:109-119. figs. 7. 1919. 



