94 



MYCOLOGY 



thallic species are all homogamic, that is, there is no difference in the 

 size of the two gametes which conjugate. This group includes such 



Fig. 28. — Zygospore formation in Sporodinia grandis from material growing on toad- 

 stool. {Slide prepared by H. H. York, Cold Spring Harbor, July 29, 1915.) 



)H=*^/ 



\=9c>i 



^^ij=f /' 



Fig. 29. — Conjugation and development of zygospores between + and — races of 

 black mould, Rhizopus nigricans. 



fungi as Absidia ccerulea, Mucor mucedo, and five other forms of Mucor, 

 Phycomyces nitens and Rhizopus nigricans (Fig. 29). Taking the con- 



