. 
silane er 
1906] OLIVE—DEVELOPMENT OF EMPUSA 195 
ultimate branch becoming a conidiophore similar to those of the 
more simple case just mentioned” (p. 142). A singular method of 
germination of the “hyphal bodies” occurs in E. aphidis and E. 
virescens, according to THAXTER’s observations. Spherical bodies, 
evidently regarded as “hyphal bodies” with highly refractive con- 
tents, germinate and send out a mass of hyphae in all directions. In 
this condition they are said to resemble a head of Aspergillus, 
although the author does not show in either of his two drawings of the 
phenomenon any trace or remnant of the central cells or “hyphal 
bodies” from which the radiating hyphae are said to arise. 
The conidium is regarded by THAXTER as having a double wall, 
and thus is to be interpreted more properly as a simple single- 
spored sporangium. 
MATERIALS AND METHODS. 
In March 1904, the writer found in horse-dung cultures in the 
laboratory a small species of fly belonging to the genus Sciara, which 
was infected with an Empusa. This small fly with its attendant 
disease has been propagated in horse-dung cultures since that time, 
and many successive generations of the insect, the larval condition as 
well as the adult, during the year and more of its cultivation, have fur- 
nished a wealth of material for an almost complete cytological and 
developmental study of this species of Empusa. A number of other 
forms of the Entomophthoreae, most of them in the fructifying stage 
of their existence, have been used for comparison, but no others have 
as yet been traced through their entire life history. Enough has been 
learned, however, to show the existence of a most interesting series 
of distinctive variations. 
My material has been killed with a variety of fixing agents, mostly 
with varying strengths of Flemming’s chromic-acetic-osmic acid mix- 
ture. The insect body was generally cut in two or pricked to allow 
direct contact of the fixing fluid and the fungus hyphae in the body 
cavity. The material was sectioned usually 3-6 » thick and stained 
with Flemming’s safranin gentian-violet orange-G, or with Heiden- 
hain’s iron haematoxylin. 
Six species of Empusa altogether have been thus studied. These 
species, determined Zaccording to the descriptions in THAXTER’S 
