580 Destruction of Obnoxious Insects by Fungoid Growths. [ August, 
have not been affected in any way by the fungi or their spores, 
the plants themselves, in some instances, have been seriously 
injured. On one occasion, recently, some experiments which had 
been commenced with much care upon Drosera rotundifolia, were 
brought to a sudden end by a mold which completely overrun 
and destroved the plant. That the air of the laboratory should 
become abundantly charged with spores, would, of course, be 
expected from the large number of experiments in the growth 
and propagation of microscopic fungi which at times are being 
conducted by the members of the classes in mycology. Indeed 
after a time the spores become so abundant that all apparatus has 
to be thoroughly cleansed and fumigation by sulphur resorted to 
in order that the experiments with the fungi themselves should 
not be defeated, 
The abundance of these spores of many kinds, including those 
of the house-fly fungus, emphasizes the fact that aphides and 
other plant insects, seen to thrive in the midst of these spores 
without any diminution of their vigor or power of reproduction, 
Although our whole experience in the cultivation of fungi, as 
might be inferred from the statements already made, as also 
nearly all observations made upon fungoid growths in general, 
indicate that the yeast fungus offers.little promise of success as a 
remedy against obnoxious insects, nevertheless the matter has ~ 
been deemed of sufficient importance to warrant a considerable 
amount of labor in the way of experimentation for the purpose 
of arriving, if possible, at some definite facts bearing directly 
upon the subject. A brief account of the methods and results of 
this undertaking is here given. All of the experiments here 
described were made on plants growing in pots in the Botanical ` 
‘Laboratory, or in the adjoining rooms, or in a large conservatory 
window, where the conditions of light, heat and moisture were 
favorable to the healthful growth of the plants experimented upon. 
In conducting the experiments I have been greatly aided by 
Instructor W. A. Henry, of the Botanical Department, who: as 
also rendered much assistance in collating information relating to 
the whole subject. l e 
Experiment No, 1—A strong plant of strawberry geranium 
(Saxifraga sarmentosa) has been allowed to become infested with 
green aphides. They are mostly confined to the flower pedun- 
cles and young tips of the runners. : 
May 13.—The plant is thoroughly sprinkled with dilute yeast bY <) 
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