15 
insect. To obtain a pure culture from the dilution-culture on 
the plate, a platinum needle is heated white-hot in a gas-flame 
and, after cooling, touched to the conidia or spores born by a 
single colony or circular growth on the surface of the agar. The 
needle is then carefully carried to a piece of potato placed in a 
glass tube, and prepared as follows: an oblong slab or stick of 
potato is placed in a test-tube and half covered with water. A 
number of these tubes are then placed in a crate of woven wire 
and thoroughly steamed for one or two hours ina steam ster- 
ilizer. This is repeated for three or four days for the purpose 
of killing any organisms present, when, after a certain interval, 
the tube is ready for use. A day or so after being inoculated 
with spores from the dilution-culture, there appears a small, 
raised, white, loose growth, somewhat like that seen on agar. 
This usually spreads, and the extent to which this proceeds de- 
pends on the species of the fungus grown. The color may remain 
white, or change to yellow or green or some other color, and 
the potato on which it grows may be colored in various ways; 
purple, dark-brown, orange and cream color are those usually 
seen. Part of the potato may send up long columns of inter- 
laced threads, which sometimes grow one or two inches in 
length, and in some species become branched. These various 
forms and colors produced during growth are great aids in de- 
termining the species in question, as they are, within certain 
limits, constant to the species. From such pure-cultures any 
amount of the fungus desired can be propagated. 
THE CHINCH-BUG DISEASE. 
The fungus used during the past season in combatting the 
chinch-bugs was obtained from several sources, that most 
generally and successfully used was obtained from a white 
grub found at Ithaca, N. Y.* Other material was obtained 
from Professor Snow of Kansas State University; some from 
a culture made by Professor Forbes of the Illinois State 
University; stillother material from Sporotrichum globuliferum 
obtained from a carabid beetle at Ithaca, N. Y., and also some 
from chinch-bugs killed in Minnesota in 1894. As the form 
first mentioned was the one most generally and successfully 
*This species (Isaria vexans Pet.) was described in Bulletin No. 97 of Cornell Univer- 
sity, Agricultural Experiment Station. It is considered an Isaria because of the 
production of true Isaria-sporophores in artificial cultures. 
