200 BOTANICAL GAZETTE [MARCH 
are beginning to appear. Whether an increase of the amount of 
protoplasm and of the number of nuclei has accompanied this 
branching is doubtful. 
It is highly probable, therefore, that in Em pusa sciarae the hypha 
which has penetrated into the body-cavity of the fly from the germi- 
nating conidium grows rapidly at the expense of the nutrient fluids 
in which it floats. After the protoplasm has increased in volume, 
the nuclei increase in number by division, and from the uninucleate 
condition, in the case of Empusa sctarae, the hypha finally becomes 
a multinucleate branching filament, such as is shown in fig. 3. 
Partition-walls in this form at first occur but sparingly; later, how- 
ever, at the culmination of vegetative activity, septa are abundant and 
branching becomes more frequent. Finally the body-cavity of the 
insect becomes completely filled with the mycelial filaments, vegeta- 
tive activity ceases, and the fructifying state begins. 
Empusa aphidis furnishes a somewhat modified vegetative devel- 
opment. The advanced condition, which is my only source of infor- 
mation in this case, shows in sections branched coenocytic hyphae, 
which appear to be but rarely divided by septa, unlike the corre- 
sponding stage in Empusa sciarae. Even after the rhizoids have 
grown out from the under side of the body of the insect (figs. 10, 11), 
the vegetative activities appear to continue, as evidenced by the fact 
that the nuclei in this instance are still undergoing division. Also 
in Empusa sp. there occurs a similar prolongation of vegetative 
activity, since at an advanced stage even fewer cross-partitions can 
be found in the coenocytic mycelium (jigs. 23, 25). 
REPRODUCTIVE STAGE. 
At the culmination of vegetative growth, the body-cavity of the 
larva appears to be completely filled with a mass of long hyphae. 
Toward the close of this stage, the larva crawls to the surface of the 
substratum or high up on the side of-the culture dish; or, in the case 
of the adult Sciara, the fly seeks a conspicuous position, as is common 
with such infected insects, and death ensues with the beginning of the 
fructifying condition. 
The initiation of the fructifying condition is marked in Empusa 
sctarae by the sudden formation of radial branches from the short 
ial 
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