414 Journal of Agricultural Research voi. xviii, no. s 



intact, and the body wall, except after molting, is very thick. When 

 resting spores are transferred from freshly opened larvae to artificial 

 media pure cultures are invariably obtained, indicating that no ex- 

 traneous organisms are present in the body cavity ; and the fact that the 

 chitin has a tendency to disintegrate in the presence of Sorosporella 

 indicates that this fungus secretes a solvent of some kind. 



Before the chitin breaks down, however, all the softer tissues dis- 

 appear, among the first of which are the fat bodies, the membranous 

 walls of which disintegrate readily (PI. 52, A). 



A colony of fungus cells which is closely opposed to a fat cell will bud 

 off more freely nearest the source of nourishment ; hence, after the wall 

 of the fat body has broken down at the surface, the colony will tend to 

 enter and, take the form of the organ, a portion of the wall of which 

 persists for some time. The result of such development is that lamella- 

 like or vermiform convoluted colonies are formed. 



Although the fat bodies disappear first as a result of the growth of the 

 fungus, the muscles, nerve fibers, malpighian tubes, and all the hypo- 

 dermal tissues gradually succumb, until eventually only fragments of 

 the tracheae can be observed. Even the alimentary tract disappears, 

 and its position is indicated merely by fragments of food. 



As the colonies of the fungus continue to grow, the individual cells 

 gradually become larger and secrete single, rather thick walls about 

 themselves, so that ultimately aggregations of spherical, rather thick- 

 walled, cohering cells are formed, which were described above as resting 

 spores or chlamydospores. The formation of resting spores marks the 

 end of the vegetative development of the fungus. These spores are in 

 fact only modified blastocysts, though they are themselves reproductive. 



The discovery of the yeastlike cells or blastocysts, the method of 

 development and mode of life of which have been considered above, 

 and the fact that they represent the entire vegetative stage of the or- 

 ganism under consideration, is of considerable scientific importance. 

 Although found by the writer for the first time in connection with Soro- 

 sporella, similar bodies were observed by De Bary (2) associated with 

 other entomogenous fungi, a fact quite unknown to the author until 

 these investigations were completed. 



De Bary found what he called "cylindrical conidia" — processes anal- 

 ogous to what have herein been called blastocysts — f ree-fioating within 

 the blood of various insects infected with Botrytis hassiana, Isaria farinosa, 

 and other similar fungi. He observed that these bodies, though some- 

 times drawn out to two or three times their original length, usually 

 remained elliptical in form and gave rise to secondary and tertiary 

 conidia on short sterigmata. Such a method of multiplication was 

 followed until the blood at the expense of which the organism developed 

 was full of "cylindrical conidia," when, because of the large numbers of 



