496 BOTANICAL GAZETTE [june 



pi. V, fig. 3) as synonymous with S. inflata, and, although Vaucher 

 figures it in cross-conjugation (pi. I, fig. 4), DeToni merely states 

 that conjugation is often lateral. Since S. inflate has been under 

 observation for so long, and these conditions have not been recog- 

 nized as characters, it would seem that we must either form a new 

 species for this plant or include these conditions in the description 

 of S. inflata. The writer is opposed to the multiplication of species, 

 but these are such distinct characteristics that plants showing them 

 should, it would seem, be classed separately. Final decision in this 

 matter, however, must be reserved until the writer or someone 

 else has had opportunity for further investigation. 



The occurrence of this species presents some new problems in 

 the general theory of sex as it applies to the filament of Spirogyra. 

 The work on the cytology of this genus has not been entirely 

 satisfactory, owing to the difficulty of staining and counting the 

 chromosomes. Chmielewski (7), in 1890, saw evidences of 

 reduction but was unable to count the chromosomes (Johnson 20). 

 In 1899 Klebahx (21) followed the reduction in the desmids, and 

 1 2 years later Trondle (27) succeeded in counting the chromosomes 

 in Spirogyra and found that a reduction takes place in the germina- 

 tion of the zygotes. He further found that 4 nuclei were formed, 

 3 of which degenerate, while "the fourth remains as the nucleus 

 of the single embryonic plant." Evidently the sex factors are 

 separated, and one or the other of them is thrown out in this 

 reduction, since a filament wholly of one sex results. 



In the case of lateral conjugation, however, it w r ould seem that 

 reduction cannot take place in the zygote, as both sexes are present 

 in the filament. Moreover, it would seem that reduction takes 

 place in the divisions just preceding reproduction. This may 



have occurred in the last division before conjugation. Let [j L 



represent a cell which upon division separates the male and female 

 factors I a 1 s 1 . These conjugating would give alternate zygotes 

 and empty cells. In this case conjugation is assumed to take 

 place between gametes derived from the same mother cell. 

 If, however, they should so divide throughout the filament that 

 the male of one mother cell should adjoin the female from another, 

 we should have the alternation of male and female, so that con- 



