32 
disease related to that of the chinch-bug. The beetles, about 
3 mm. long, were partially covered with a dense, white, felted 
coat of mycelium, the fungus breaking forth from the junction 
of the prothorax with the abdomen, and from under the wing- 
covers (Fig. 15). From one end of each beetle there arose a 
slender Isaria-sporophore, about 5 
mm. long, and 1mm. in diameter. 
In one case the sporophore is cla- 
vate, in another flattened and tap- 
ering. Two sporophores arise from 
one of the beetles. A microscopic 
examination shows the sporophore 
and the felted mass at the base to 
be covered with clusters of conidia 
resembling those of Sporotrichum 
globuliferum, but measuring usually 
from 1? to 24 microns in size. 

FIG. 15..-Bark-beetle attacked by 
Isaria tomicti. Original. 
Description.—A_ dilution-culture was made and pure cultures started on 
potato. In agar-agar plate-cultures the development is as follows: in 
about one day after sowing the conidia become swollen and put out one, 
two, or three slender germ-tubes, fig. 16, a, which rapidly lengthen, and 
after two days become branched to a considerable extent. Vacuoles are 
numerous at this period, fig. 16, b. After about four days the threads ap- 
pear above the surface of the agar, anastomosing freely both above and 
below the surface, fig. 16,c. After about a week conidia are borne on the 
threads, in clusters with a verticillate arrangement. Short offshoots 
from the main threads bear whorls of from two to six short branches, 
which in turn bear whorls of either sterigmata or branches; these branches 
bear at their extremities groups of from two to six or more flask-shaped 
sterigmata which bear the hyaline conidia at their apices on short, 
minute pedicels, usually in clusters of from two to eight, fig. 16, d and e. 
These clusters grow and produce more branches until, after about eleven 
or twelve days, they appear like dense, rounded balls (Fig. 16, f and g) 
borne on the main threads, after the manner of Sporotrichum globuliferum. 
The separate colonies have, by this time, grown until they are beautiful, 
circular, fluffy masses raised from the surface of theagar. ‘They are from 
5 to 10mm.in diameter. In places where they are crowded the growth 
is not strongly raised from the surface of the agar, but quickly becomes 
covered with clusters of conidia causing it to appear farinaceous. In 
more favorable places, less crowded, the growth rises in strong circular 
colonies, which are loose and fluffy, and occasionally rise 5 or 6 mm. from 
the substratum. 
