372 Illinois State Lahoratory of Natural History. 



Bacillus entomotoxicon Duggar. 



Occii/rrence. — In the blood and tissues of diseased squash- 

 bugs. 



Morp/iology . — Short bacilli 1.2—1.8 /i X0.6— 0.8 fx, single 

 or in pairs, motile, not producing spores. 



Preparations stain well in most of the anilines, the 

 bacilli often staining much more deeply at the poles, 

 consequently showing a banded or belted appeai'ance. 



Gj-oioth and pathogenic characters. — An aerobic and fac- 

 ultative anaerobic organism, producing on nutrient agar- 

 agar a dirty white colony often characterized by promi- 

 nent fan-like radiations. Stab cultures on nutrient gela- 

 tine give liquefaction on the second or third day, soon 

 assuming the shape of an inverted lamp chimney, and 

 after standing one month the gelatine is colored wine- 

 red. Milk is rapidly coagulated and the coagulum in 

 great part dissolved, the odor attending this growth on 

 milk being exceedingly vile. Nitrates are not reduced. 

 It grows well at living-room temperature, but is easily 

 killed by exposures to high temperatures. 



The infected insect becomes sluggish a few hours before 

 death, and at death it is slightly darker and softer. 

 After death the insect is slightly swollen, darkens rapidly, 

 and soon contains only a mass of gruel-like fluids. 



Sterile or active infusions from the growth on agar 

 contain a principle toxic for many species of insects, as 

 shown by temporary immersion. 



SUMMARY. 



Under the specific description are summarized the 

 leading facts relative to the structure of this organism 

 and to its growth on the usual culture media. It is 

 necessary to add a few brief statements embodying 

 some of the results of general oecological interest. 



Bacillus entomotoxicon is the cause of a characteristic 

 disease of the squash-bug, first observed as an epidemic 

 among bugs in a laboratory breeding-cage. 



