THE ENTOMOLOGIST. 235 
; dying in this position?—Mr. Woodhouse describes very 
minutely the appearance of flies found in this condition. I 
offer the following explanation, which is in part problematical, 
and is almost entirely derived from the publications of others. 
The disease is attributed to a cryptogamic plant, but whether 
a fungus or a member of the comprehensive and somewhat 
heterogeneous order of Alge, we have no positive decision ; 
botanists seem divided in opinion on the point. Amongst 
+) those who have written on this plant are Pringsheim, Archer, 
De Bary, Unger, Thuret, Tute, Gnffith and Henfrey, Braun, 
i. Robin, Cienkouski and Nageli. The prevailing opinion 
seems to be that it is an imperfect terrestrial form of 
Saprolegnia ferax, a fungus of which I know nothing except 
the name. This particular form is called Sporendonema 
Musce, and has its habitat in the bodies of flies. Empusa 
aulica is another fungoid growth of a like nature. These 
fungi—I call them so, not for the purpose of expressing an 
opinion on their true character, but simply for convenience— 
these fungi, or rather their spores, are found to exist in multi- 
tudes in the bodies both of diseased and of apparently healthy 
flies: the spores are found floating in the blood of the flies; 
but in a short time they seem to exhaust all the fluid matter, 
and then expanding, or rather lengthening into filaments, 
called mycelia, they at last completely fill the body of the fly 
with a substance resembling cotton-wool, and the fly at last 
succumbs to starvation, although to all appearance replete 
with food, when the fungus makes its appearance at the 
interstices of the segments and at the spiracle, and throws 
out spores all round, forming a kind of circle round the fly, 
entirely composed of these spores and the filaments which 
emanate therefrom. There seems to be something glutinous, 
or to say the least, adhesive, in this fungus, for through its 
instrumentality the fly becomes so firmly attached to the 
pane that it is frequently impossible to remove it without the 
loss of a leg. With regard to the fly being fixed to the 
window-pane, I can only suggest that this circumstance 
exhibits no selection on the part of the fly, but simply arises 
from the circumstance that in this selection they are pecu- 
liarly exposed to observation.— Edward Newman. 
James Deane.—Musca pluvialis—I enclose a small 
sample of a species of fly, by which I was much troubled for 
