284 



Mycologia 



and S. octosporus on old currants presumably from Greece. The 

 appearance of the last at Chapel Hill is the first reported occur- 

 rence, so far as we know, of any of the genus on the American 

 continent. Schionning* was the first to publish observations on 

 the conjugation of S. octosporus. He found that the cells des- 

 tined to form the ascus divide into daughter cells which do not 

 separate completely, but remain attached at a certain point. After 

 some time the partition at the point of attachment is absorbed 

 and the two sister cells fuse to form an ascus with eight spores. 



Guilliermondf in 1903 confirmed these observations in large 

 part but thought that while the fusion may take place simply by 

 the solution of the partition wall it is generally brought about by 

 the formation of two short projections just above the point of 

 contact, which meet at their tips and fuse.f. 



Guilliermond also studied the nuclear behavior and found that 

 the two nuclei fuse in conjugation and then divide into eight 

 daughter nuclei around which the eight spores are formed. This, 

 then, is to all appearances a true case of isogamous sexual re- 

 production. In a later paper§ Guilliermond reports further obser- 

 vations on this yeast and thinks he has exaggerated a little in 

 saying that it is always sister cells that fuse. From certain 

 appearances, which he figures, he thinks that the fusing cells may 

 occasionally be separated from each other by several cell divisions. 



In our study of the development of Schizosaccharomyces octo- 

 sporus, extending over several months, we largely confirmed the 

 observations of the authors above mentioned. However, we saw 

 no indication whatever of fusion between any but sister cells, nor 

 any sign of conjugation through projecting tubes or processes. 

 In plate LV, we give a series of drawings showing conjugation 

 (figs. 14 to 25). The condition shown in figs. 17, 18 and 25 is not 

 due in our opinion to the fusion of elongated processes, but to the 

 drawing out of the cells after fusion. The typical series is per- 

 haps best represented by figures 14, 15, 16, 20 and 21. Where 



* Compt. Rend, des Brau. Lab. Carlsberg. 4: 1895. We have not been able 

 to see this paper. 



t Rev. Gen. de Bot. 15 : 1903- 



% This method reminds us of the conjugation in certain species of Spirogyra 

 where neighboring cells may fuse by such a projection. 

 § Rev. Gen. de Bot. 17: 337. 1905. 



