GOLDSTEIN: RESTING SPORES OF EMPUSA MUSCAE 319 
data to confirm this view are so far lacking, but it seems to be a 
matter of common observation. No one records finding the 
fungus before July in this country. 
Brefeld found that the conidia of E. Muscae were very short- 
lived, not living more than a few days. Not being able, during 
all his observations, to find any resting spores, sexual or asexual, 
he was puzzled as to how the fungus could live through the 
winter when there were no flies to pass on the infection. He 
came to the conclusion that the disease must be endemic in the 
South, where the flies are active throughout the winter, and that 
as summer comes on the disease travels northward. Brefeld 
concludes, on the ground of his own and Dr. Méller’s failure to 
observe any form of resting spore either in Europe, Africa, or 
South America, sia Empusa Muscae has lost the power to pro- 
duce resting spore 
Olive seeded 3 in keeping the fungus, E. Sciarae, on a small 
fly, Sciara sp., under observation for a whole year, and in all 
that time did not observe the formation of resting spores at all. 
He notes that the spontaneous appearance of the fungus in the 
laboratory cultures of the fly as early as March renders Brefeld’s 
hypothesis improbable for this case. Olive concludes that 
E. Sciarae probably lives upon the successive generations of the 
flies breeding in the dung of warm stables through the winter. 
The ability of Empusa Sciarae to grow and reproduce asexually, 
attacking one generation of flies after another without the inter- 
vention of a sexual stage or resting period, is evident from 
Olive’s cultures maintained throughout the year. 
Thaxter finds that Brefeld’s idea of the fungus moving north- 
ward each year with flies from the South is refuted by his ob- 
servations that the disease appears in the South in July and that 
it regularly makes its appearance in the North at the same date. 
Lebert, in 1857, in his paper on the fungous disease of flies, 
shows several figures which Thaxter refers to as possible resting 
spores. These figures do not seem to me to be at all likely to 
be representations of the resting spores of E. Muscae. 
Giard, in 1878, stated that the reason resting spores of 
E. Muscae had not been found was that they are not formed in 
flies that have died indoors and that they do not occur in the 
interior of the fly’s body. He found irregularly rounded, thick- 
walled cells on the outside of the fly’s body, which he believed 
