Jan. IS. 1920 Further Studies of Sorosporella uvella 405 



walls; cohering in groups and arising from yeastlike, hyaline, elliptical budding cells. 

 In mass, brick-red in color ("Brick Red" Ridgway) and powdery. Conidia thin- 

 walled, hyaline, 4 to 6 by 9 to 11 microns in diameter, abjointed successively from 

 bottle-shaped or almost subulate branchlets of simple or branched conidiiferous 

 septate hyphae and adhering after abjunction. 



Hosts: Cleonus punctiventris Germ. (Coleoptera), Russia; Agrotis segetum Esp. 

 (Lepidoptera), Russia; Euxoa iessellata Harr.; Nociua c-nigrum L.; Agrotis ypsilon 

 Rott.; Feltia subgothica Haw.; F. jaculifera Guen.; and various other cutworms 

 and noctuids in the eastern United States and Canada. 



LIFE HISTORY 



An opportunity was first afforded the writer in June, 191 6, to study 

 this fungus on infected cutworms received from College Park, Md. The 

 insects showed no external signs of fungus attack even though dead, 

 but when they were broken open a brick-red, powdery mass escaped 

 from the larval shell (PI. 51, A) which when examined microscopically 

 was found to consist of spherical or subspherical, somewhat reddish- 

 colored, moderately thick-walled cells. 



Attempts were made at once to cultivate the fungus on artificial 

 nutrients, and the usual plate isolation method was employed with 

 potato agar as a medium. The results of the first tests were somewhat 

 discouraging, but finally a pure culture was obtained, on another nutrient, 

 from which subcultures have been made continuously since 191 6. The 

 following discussion is therefore based upon a study of diseased insects 

 collected in the field, as well as on a study of insects that were inoculated 

 in the laboratory from cultures on artificial nutrient media. 



The thick-walled spherical cells as they occur within the host may be 

 solitary, but more often they cohere in characteristic masses or aggre- 

 gations (PI. 51, H). Many show wartlike protuberances (PI. 51, E), and 

 others show coherent fragments of the walls of cells to which they were 

 previously united (PI. 51, E). 



As will be shown in another connection, they may retain the power 

 of germination for a considerable period because of their rather thick 

 walls; and since they are, therefore, functionally analogous to similar 

 thick -walled cells of the Entomophthorales and many other fungi, they 

 may be termed resting spores or chlamydospores. 



If a water mount is made of these resting spores and pressure is applied 

 to the cover glass, it becomes evident that the individual cells are very 

 firmly coherent, since their association is broken up with considerable 

 difficulty. If sufficient pressure is applied, however, the homogeneous 

 character of the resting-spore masses becomes apparent. The masses 

 are resolved into their constituent cells, which prove to be undiffer- 

 entiated and uniform throughout. 



It should be stated in this connection that specimens collected in the 

 field are found almost invariably in the condition just described, because 

 the resting spores, which mark the tennination of the development of 



