318 GOLDSTEIN: RESTING SPORES OF EmpusA MUSCAE 
material appeared between the dark segments of the abdomen 
and that this condition was soon followed by a discharge of 
conidia. 
Cohn gave the name Empusa to the fungus and described 
it as a three-celled organism. On tearing the tissues apart, he 
found the swollen hyphal cell, which he called the root-cell, 
within the body; arising from this he observed the long tube- 
or stalk-cell—the conidiophore or second cell; the latter gave 
rise to a third cell or conidium. He was not able to find within 
the fly’s body any mycelial growth like that characteristic of 
other fungi. 
In 1870, Brefeld described a series of observations on the 
infection of the fly by the conidia of the fungus, on the germina- 
tion of the conidia, and on the growth and development of the 
fungus within the host’s body. Brefeld found that the conidia 
germinated upon the fly’s body, and that the germ tubes were 
able to pierce the thin integument of the under side of the body 
directly. Here the germ tubes give rise to large cells. These 
large cells, feeding upon the fat-cells and body-juices of the fly, 
give rise by budding to other large cells. From these cells the 
conidiophores finally grow out, so that the insect’s body appears 
to be completely filled with these hyphal tubes. In five or six 
days after infection the insect dies, after attaching itself by its 
proboscis toa surface. Each hyphal tube ends with the building 
of aconidium. The throwing off of spores lasts two days. The 
rest of the conidiophore, after the discharge of the conidium, 
disintegrates in the fly’s body. 
Thaxter’s description of the vegetative development of the 
genus Empusa seems to accord with that given by Brefeld for 
E. Muscae. According to Thaxter, the germ tube of a conidium 
enters the host’s body and there grows rapidly in the body-juices 
of the insect. It does not produce a mycelium, however. 
Short, thick cells are formed, which reproduce rapidly by budding 
and, finally, completely fill the host’s body. Thaxter has given 
the name “hyphal bodies”’ to these short, thick cells. 
The house fly disease, as has been commonly observed in 
this country and Europe, seems to become most evident and 
widespread in the fall of the year. The flies appear in early 
spring, become more and more plentiful during the summer and 
fall, and again disappear during the cold months. Statistical 
