29 
tivated spores in sufficient quantity to permit their direct appli¬ 
cation in the field. This would require, however, a very large 
central plant for cultivation and distribution, and is not to be 
recommended until the economic value of the whole method has 
been more satisfactorily tested. 
It seems barely possible that culture methods may be so simpli¬ 
fied by further experiment as to bring them within the resources 
of the intelligent and careful farmer. 
9. The precise economic value of this method is not as yet, by 
any means, fully known. It seems to be, in Illinois, at best a 
means of hastening the appearance of the muscardine and of ac¬ 
celerating its spread among chinch-bugs under favorable weather 
conditions; but how much it may actually hasten either the appear¬ 
ance or the spread remains yet to be ascertained. 
We may say , in brief, that the agricultural effect of a chinch- 
bug attack is to hasten and intensify the evil consequences of 
drouth; and that the contagious disease of that insect here treated 
has merely the effect to hasten and intensify the beneficial con¬ 
sequences of wet weed her. 
A considerable number of additional results of minor economic 
interest may be found stated under the discussions of experiments 
with which the account of the work for each year is introduced. 
WORK OF THE YEAR 1891. 
The work of the year 1891 upon the contagious diseases of in¬ 
sects, and especially of the chinch-bug, was limited wholly to. 
laboratory experimentation, no field experiments of any descrip¬ 
tion being made. It was in continuation of the previous 
work of my office, as described in my earlier reports, but was im¬ 
mediately suggested by a spontaneous outbreak of white muscar¬ 
dine in a collection of hibernating beetles ( Disonycha pennsyl- 
vcmica) kept under my observation during the spring of this year, 
and by an artificial culture of the fungus of white muscardine 
(Sporotmchum globuliferum) on agar-agar received from Prof. 
Thaxter, of Harvard University, about May 15. 
The experimental work of the season consisted of cultures of 
Sporotrichum and of contagion or infection experiments with chinch- 
bugs, cabbage worms, and other insects, by the use of the spores 
of this same fungus as an infection material. Culture experi¬ 
ments were made in part by the sterilization methods of the bac¬ 
teriological laboratory, and in part without sterilization, in the 
open air. Five of the sterile cultures were made on peptonized 
agar-agar, twenty-two on corn meal mixed with beef broth, and four 
each on sawdust, middlings, and bran, wet up with the same 
liquid. The open-air culture experiments were twenty in number, 
thirteen on various mixtures with meal, two on horse droppings, 
one on bread, two on boiled beef, and two on raw egg. 
The contagion or infection experiments numbered forty-one, 
twenty-one of them with chinch-bugs, three with cabbage worms 
and seventeen with miscellaneous insects. In the chinch-bug work 
