198 BOTANICAL GAZETTE {MARCH 
drier, the insect developed frequently into the adult fly, which itself, 
after ovipositing, generally died of the disease. 
In order to determine whether the disease could be carried from 
larval to adult condition, I have examined many pupae, but only in one 
or two instances have hyphae been found. In one case in which a 
young insect was struggling to get out of its pupal shell, a few Empusa 
hyphae were noted when the body was cut open, together with many 
small eggs and globular fat-bodies. When cultures were kept at 
some distance from infected ones, in an adjoining room, Sciara fre- 
quently developed to maturity by hundreds and died finally a natural 
death, evidently without infection. 
Resting spores in this species, as in E. muscae, have not been 
observed ; hence the puzzling question confronts us here also as to the 
method of wintering of the fungus. An interesting suggestion is made 
in this connection by the spontaneous appearance of Empusa sciarae 
in laboratory cultures as early in the spring as March, in 1904. This 
fact apparently still further renders useless BREFELD’s hypothesis as 
to the migration of the fungus north from warmer countries. The 
host, in this case, must have been breeding in the dung of the warm 
stables all through the winter, and it is quite reasonable to suppose 
that the short-lived fungus must have been continued at the same time 
on successive generations of insects. The successful cultivation of the 
form for more than a year in the laboratory gives additional reason for 
this belief. It is possible that Empusa muscae and such similar forms 
may have lost their sexual stage, because of their success in propaga- 
ting the disease by means of conidia alone. It is well known that a 
few house-flies survive the winter by hibernation or otherwise, and it is 
probable that some of the individuals during the winter may continue 
breeding in stables or in other favorable places, and in this way carry 
over the disease, even in cold climates. 
Living larvae of Sciara furnish beautiful material for a study of the 
vegetative conditions of this type of Empusa. When placed on a 
slide in water, a glance with the naked eye is sufficient to determine 
whether the larva is infected or not, since the diseased individuals are 
whitish in appearance, due to the presence of the more or less copious 
mycelium, while uninfected ones are transparent. Under the micro- 
scope, the diseased Jarvae show clearly the long, branched, mycelial 
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