184 PROCEEDINGS OF THE AMERICAN ACADEMY, 



which shows a more or less definite structure, which Cavara ('99) has 

 considered to be reticulate, but which, in the preparations studied, is 

 distinctly alveolar. This difference in appearance may be due to 

 different nutritive conditions, or more probably to difference in fixa- 

 tion. The nuclei are relatively few, and show, as a rule, regular spac- 

 ing. Each hyphal body sends up a long hypha to the surface of the 

 body of the host. Into this hypha pass a varying number of nuclei. 

 In the conidiophore, as this hypha may be called, the nuclei attain 

 their greatest size (Figure 19), owing, in all probability, to the active 

 metabolism necessary in connection with the formation of the conidia. 

 The nuclei in the conidiophore, as in the hyphal body, show a strik- 

 ingly regular spacing, and in the older portions a septate condition is 

 occasionally to be seen, these septa cutting off mostly bi-nucleate cells 

 (Figure 17). At the top of each branch of the conidiophore the cyto- 

 plasm becomes much denser, showing an upward pressure and conden- 

 sation at that point. Under this pressure a small protuberance soon 

 appears, forming the young conidium, into which passes the dense 

 cytoplasm (compare Empusa, Figure 24). A single nucleus enters the 

 young conidium, becoming smaller and denser during its passage. The 

 conidium is then cut off. There is never any nuclear-division during 

 this process, and the single nucleus of the conidium comes directly 

 from the conidiophore. The mature conidium (Figure 18) is a com- 

 paratively thin-walled structure, densely filled with very fine-meshed 

 cytoplasm and with a single much condensed nucleus. 



Zygospores. 



The formation of the zygospores has been studied by the writer in 

 E. Americana, and the results there obtained have been confirmed by 

 a further study of E. echinospora and E. Geometralis. There has been 

 hitherto no account of the cytological processes involved in the for- 

 mation of sexual resting-spores in any of the genera of the Entomoph- 

 thoraceae, with the exception of Basidiobolus, in which the conditions 

 have been generally recognized as peculiar and difficult to bring into 

 relation with the processes known in the other Phycomycetes. 



Entomopkthora Americana shows two methods of zygospore forma- 

 tion. In the first case two hyphal bodies fuse at a point near their 

 tips (Figure 12); the young zygospore then buds out at this point of 

 fusion, in a manner similar to that seen in Piptocephalis, among the 

 Mucorales. In the second case, the fusion of the two hy])hal bodies is 

 distinctly lateral (Figure 11), forming what may be compared to an II 

 with a very short bar. The young zygospore in this case buds out 

 from one of the gametes, at a point usually far removed from the point 



