12 State University experimental Station. 



of the boxes, and in stripping the boxes of infected bugs the soil was care- 

 fully raked over and picked from after the fungus-covered bugs had been 

 gathered from the surface. In this way the number of fungus covered bugs 

 which a single infection box was capable of yielding was greatly increased, 

 and at the same time the soil was kept in a loose and friable condition and 

 well aerated throughout, a condition necessary to the best development of 

 the fungus, since a liberal supply of oxygen is essential to it. 



In infecting fields under our personal supervision, we found it an excel- 

 lent plan to remove half of the earth with its contents of Sporotrichum-cov- 

 ered bugs from the infection boxes, and to work the soil over thoroughly, in 

 order to distribute the spores through it as evenly as possible, and then to 

 scatter this soil at intervals where the bugs were most numerous in the 

 fields. A new supply of soil and healthy bugs was put into the infection 

 boxes, and on the following day the second half was distributed in the field 

 and the box replenished as before. 



By the method just outlined, our infection boxes worked more satisfac- 

 torily than in any previous year, and we were able to supply without any 

 delay the largest demand ever made upon us. 



7. — Artificial Cultures. 



In regard to artificial cultures of Sporotrichum, it was found that the 

 fungus would grow on all the nutrient substances tried, but especially well 

 on Irish potato and squash. Turnip, onion, sweet potato, horse and rabbit 

 dung, and decoctions of various substances, taken alone or stiffened with 

 agar agar, were tried successfully, but the vegetables gave a more vigorous 

 growth than the other media. Plate I, figure 1, is from a photograph of a 

 culture of Sporotrichum grown on squash ; figure 2 shows a growth on Irish 

 potato. Plate II, figures 1 and 9, show Sporotrichum grown on the surface 

 of a liquid decoction of squash; figure 2 shows a growth on rabbit dung; 

 figure 3 on horse dung ; figure 4 on squash ; figures 5 and 8, Sporotrichum 

 growing on Irish potato, transferred from a growth found on an insect in a 

 wood near a cultivated field on January 10, 1895; figure 6 shows a culture 

 on turnip, and figure 7 on onion. 



Experiments made during the fall of 1894 in infecting chinch bugs with 

 Sporotrichum grown on nutrient substances, while not conclusive, indicated 

 that the fungus thus cultivated does not lose its power of killing insects. 

 Experiments were made with Sporotrichum grown on Irish potatoes, horse 

 dung, and other substances, and the bugs used were collected in September 

 and October, 1894. In some cases, the first remove of Sporotrichum from 

 the growth on the bug was used; in others, the second, third and fourth re- 

 moves were employed. In several of these experiments where Sporotrichum 

 of the fourth remove grown on horse dung was used the bugs exposed to the 

 infection became covered with a growth of the fungus, but only in small 

 numbers, and after a relatively long time. Check experiments, in which 



