60 
THE YEAR 1892. 
The experimental work upon the contagious diseases of insects 
during the year 1892, was practically a continuation of that of the 
preceding year, differing from the latter especially in the fact that 
in addition to work with Sporotrichum globuliferum , experiments 
were made with two other entomogenous fungi— Botrytis tenella 
and 1 sciria leprosn; that a beginning was attempted with field ex¬ 
periments with Sporotrichum upon chinch-bugs; that the labora¬ 
tory contagion and infection experiments were extended to a large 
number of additional species of injuri >us insects; that cultures on 
agar were studied with reference to the rate of growth and de¬ 
velopment of Sporotrichum upon that medium; and that several 
cultures were made for the purpot-e of asceitaming the length of 
life of the dry spores of Sporotrichum. 
The scarcity of the chinch-bug in parts of the State readily ac¬ 
cessible to us, made the field contagion experiments of little effect; 
and the culture experiments, with the exception of those made for 
the purpose of testing the persistent vitality of fungus spores,, 
were mostly made merely to provide a supply of spores for use 
in making infection experiments on various insects, or else were 
sequent to such experiments, whose results they were intended to 
verify. 
The agar cultures gave us, as might have been anticipated, sub¬ 
stantially the same rite of development of Sporotrichum as that 
ascertained for corn-meal cultures in 1891, visible growth occurring 
on the second or third day after the sowing of the spores, notice¬ 
able development of heads of spores appearing at about the 
seventh day, and the first conspicuous ripening ranging from seven 
to fifteen days. It is to he noticed that cultures made in March 
and October, developed much more slowly, than those made in 
July. As no effort was made at temperature control, these vari¬ 
ous experiments were, of course, affected by the weather of the 
season. The spores of Sporotrichum, globuliferum were proven by 
experiments 1 and 2 to live at least six mouths when thoroughly 
well dried out; by experiment 3 to live eight months; and by ex¬ 
periments 27 and 49 to be capable of generous growth after nine 
months of dessication. On the otl.er hand, in Nos. 69 and 70 are re¬ 
corded failures of germination under entirely favorable conditions 
after eleven months’ drying out. 
A single experiment (No. 23) gave the interesting information 
that these little spores may germinate in water in a few hours, 
and that a considerable growth of hyphse may be made within 
twenty-four hours. 
A point of notable interest in the life history of Sporotrichum 
globuliferum was brought out by an infection experiment upon 
white grubs referred to under No. 51. These insects, buried 
lightly in the earth after death by muscardiue, threw out upon 
the surface of the ground a delicate sheet or mat of mycelial 
growth, which ultimately bore spores abundantly upon its free 
margin. (See Pi. VII., Fig. 8, 9.) The identity ot this remarkable 
Isaria form with the original Spoiotrickum, was demonstrated by agar 
