350 JUinois State Laboratory of Nataral History. 



the addition of a few drops of naphthjlamiue chloride 

 and a small quantity of sodium sulphanilate. The 

 formula for the nitrate solution used is as folio ^vs: 



Water 1,000 c.c. 



Peptone 1 grm. 



Potassium Nitrate 0.2 grm. 



INFECTION EXPERIMENTS WITH THE SQUASH-BUG. 



Laboratory Experiments. 



In addition to the introductory experiments it is 

 necessary to describe in some detail the numerous in- 

 fections made in the laboratory under various condi- 

 tions. It was my practice to accompany every experi- 

 ment, or series of experiments, with a check suV)jected to 

 similiar conditions, but without inoculation. Moreover, 

 with all the cages and contents of cages, sterilization 

 by means of heat and corrosive sublimate was employed 

 as far as was compatible with the size and nature of 

 the materials employed. Whenever possible, the bugs 

 used for experimental purposes were first kept in the 

 laboratory for two or three days, in order to watch for 

 any "spontaneous" outbreak of the disease. 



Experiment 3. — In a breeding-cage which had served 

 as a check on some previous work, there were twenty- 

 eight adult squash-bugs and twelve large nymphs. These 

 insects had remained perfectly healthy throughout, and 

 on August 12 each of the individuals was inoculated by 

 touching to its body the mixed fluids from a diseased 

 bug out of Experiment 1. In four days eighteen bugs 

 were dead, ten adults and eight nymphs; on the fifth 

 day twenty-four were dead, fourteen being adults and 

 ten nymphs; and during the next four days there were 

 only six deaths, one nymph and nine adults remain- 

 ing. A second inoculation was then made in the 

 same manner as before, and five days thereafter one 

 half of the remaining ten were dead. Four adults sui'- 

 vived both inoculations. In this experiment it was no- 

 ticeable that the nymphs died i-apidly duj-ing the first 

 few davs. 



