34:4 Illinois State Laboratory of Natural Iliatory. 



scribed, — but the usual shrinking of natural death oc- 

 curred. It is probable that dead bugs placed on a wet 

 surface might absorb moisture and show an appearance 

 somewhat similar to the disease effect, but this is only 

 a surmise. 



ISOL.4^TION CULTURE AND GROWTH ON AGAR-AGAR. 



A number of dilution cultures were made during the 

 progi'ess of these preliminary experiments, but the re- 

 sults were so uniform that only one such culture will be 

 reported in detail. For some of the earliest dilution 

 cultures dead insects were necessarily employed, and the 

 body fluids were thus greatly mixed. Even with these, 

 howevei-, cultures were obtained which gave one form of 

 colony in great preponderance, while a few other forms 

 were confined to scattered colonies in the original dish. 

 Here, also, the abundant form was identified as a 

 bacillus, rreliminary experiments demonstrated that 

 this form was an effective pathogenic agent for squash- 

 bugs; and as soon as sick insects were available, every 

 precaution was taken to secure a culture with the least 

 practicable admixture of foreign forms. 



All the necessary apparatus having been properly 

 sterilized, a sick nymph was thoroughly washed with 

 cori-osive sublimate solution, and a fold in the soft body 

 wall of the abdomen was caught in the forceps, and slit 

 with the scissors in such a manner as not to disturb 

 the alimeutai'y organs. A small amount of the exuded 

 body fluid was then transferred with a platinum needle, 

 in the usual manner, to a tube containing peptonized 

 nutrient ngar-agar at the prescribed temperature. After 

 shaking well, several transfers were made from this first 

 tube to a second, and finally to a third; and the con- 

 tents of each were poured into a Petri dish. To the 

 nutrient agar used in these tubes was added a small 

 quantity of squash-leaf decoction, and as this was found 

 to 1)6 of advantage, it was continued in all subsecjuent 

 affar cultures. 



