89 



Conjugation in Spirogyra. 



By F. M. Andrews. 



A large (jiiaiitity of Spircigyra crassa and Spirogyra ;omimiiiis were 

 found in .September in a pond and upon examining it both forms were 

 found to be conjugating. Not only was the species Spirogyra crassa found 

 conjugating togetliei". but sometimes Spirogyra crassa was found conjugat- 

 ing witli Spirogyra communis. The smaller one of tlie two filaments in 

 Fig. 1 is Spirogyra commmiis and the larger one Spirogyra crassa. The 

 contents of tlio majority of the cells pass from the larger species to the 

 smaller ones forming a z.vgospore. and in other cases the contents of most 

 of the cells of Spirogyra communis pass into the cells of Spirogyra crassa. 

 Some of tlie forms her.:> shown which had not begun to conjugate began 

 and completed conjugation when brouglit into the laboratory. In an 

 earlier paper T have called attention to the interesting facts the hybrid 

 forms mav show.' 



Figure 1 . 



Generally it is the case that when Spirogyra is conjugating the con- 

 tents of the cells of one filament will all pass over into the cells of the 

 otlier filament near it, as text-books and authors state. Tliis is by no 

 means always the case as is shown by Fig. 2.= In some cells, as will be 

 seen at A and P.. Fig. 2, the contents of the contiguous cells in the same 

 filament go to corresponding contiguous cells in the other filament, but the 

 contents of other cells as C and D, Mg. 2, do not do so, but go in the 



1 Andrews, F. M. Bulletin of the Torrey Botanical Club, Vol. 38, p. 29G 



2 Bennett and JIurrar. p. 266. 



