344 THAXTER. 



PLATE I. 



Endogone pisiformis Lk. 



Figures 1-5. Successive stages in the formation of zygospores. 1-4, obj. 

 J, oc. 4; 5 obj. J, oc. 2. 



Figure 6. Mature spores with gametes still attached. 



Figure 7. Peculiarly differentiated hypha forming the superficial tomen- 

 tum of a young individual. 



Endogone multiplex Thaxter. 



Figure 8. Mature spore showing hyphal envelope. 



Figure 9. Mature spore with discrete gamete attachments, treated with 

 KOH. 



Figure 10. Larger and smaller spore-groups surrounded by envelope with 

 incorporated humus-material. 



Endogone tuberculosa Lloyd. 



Figure 11. Section of sporocarp showing disposition of sporogenous areas, 

 (light), with surrounding and penetrating earthy envelope (dark): magnified 

 about seven times as reduced. 



Figure 12. Portion of gleba showing spores and pseudoparenchymatous 

 hyphal tissue. 



Figure 13. Spore showing envelope and origin from gametes. Zeiss J, 

 oc. 1. 



Figure 14. Fully matured spore with greatly thickened exospore. 



Figures 15-16. Spores of more elongate type. 



Endogone incrassata Thaxter. 



Figure 17. Section of a portion of sporocarp, showing peridium and gleba 

 with fully mature and more immature spores. 



Figure 18. Spore showing characteristic fatty contents and probably 

 sexual origin. Zeiss D, oc. 12. 



Figure 19. Fully mature spore with greatly thickened exospore and com- 

 pacted surrounding hyphae. 



Endogone ludiflua Berk. 



Figure 20. Showing origin of zygospore from dissimilar gametes. 



