RIDDLE. — UN THE CYTOLOGY OF THE ENTOMOPIITHORACEAi:. 171) 



species put in Entomophthora, they are typically un' -nucleate, it seems 

 best to consider them as two distinct genera. 



The results given in this paper are based upon a study of preparations 

 from the following species. 



1. Emimsa Grylli, Nowakowski, on Hyphantria larvae (the "Fall 

 Web-worm "), and on the larvae of Spilosoma. 



2. Entomophthora Americana, Thaxter, on the imagines of Musca sp. 

 and various other large flies. 



3. i.'Uso an undescribed form closely related to E. Americana, found 

 by Professor Thaxter in various localities in New England, and called 

 in this paper Entomophthora "a'." The form "a-" resembles E. Amer- 

 icana in hosts and in conidia, but differs from it in the zygote, the 

 epispore of which is smooth in Americana, but is furnished with bullate 

 processes in Entomophthora "^." (See Figure 16.) 



4. Entomophthora echinospora, Thaxter, on the imagines of Sapro- 

 myza (a small yellow-winged iiy). 



5. Entomophthora Geometralis, Thaxter, on the imagines of a 

 geometrid-moth. 



6. Entomophthora rhizospora, Thaxter, on caddis-flies. 



7. Entomophthora Et'esenii, Nowakowski, on a species of Aphis. 

 Most of the material was fixed in 0.75 % chrom-acetic acid, which 



gave satisfactory results, except for the more mature stages of the 

 resting-spores, when it became necessary to use hot sublimate-acetic. 

 Flemming's weaker solution was also tried, but seemed to be no 

 improvement over the chrom-acetic mixture. It is worthy of notice, 

 however, that material gave excellent preparations after being left in 

 Flemming's for some weeks (cf. Chamberlain, : 01, p. 27) ; the figures 

 in Plate I illustrating mitosis were drawn from such material. Small 

 pieces of the hosts infected with the fungus were imbedded in paraffin 

 by the usual procedure, and sections were cut either tliree or six 

 microns in thickness. 



In staining, safranin-gentian-violet gave decidedly the best results. 

 The use of orange G in connection with these stains seemed to have 

 no added advantage. Heidenhain's iron-alum-haematoxylin was also 

 tried, but was a decided failure, as the stain showed too great affinity 

 for the general cell-contents. Unless otherwise stated the preparations 

 from which the plates were drawn were fixed in chrom-acetic and stained 

 in safranin-gentian-violet. 



