50 



Annals Entomological Society of America [Vol. X, 



The locust to be inoculated was held between the thumb 

 and forefinger of the left hand and a drop of the suspension was 

 injected between the first and second abdominal sternites by 

 means of a very fine hypodermic needle. 



The first lot inoculated were all dead in five days, owing 

 doubtless to the fact that a rather strong suspension of the 

 original pure culture was used. The second, third and fourth 

 lots did not all die, some remaining alive for upwards of twenty- 

 three days. After the fourth inoculation no injected locusts 

 survived. 



Some of the locusts of the second, third and fourth lots 

 which were apparently healthy after twenty-three days were 

 killed and the intestinal contents examined, and we found that 

 the coccobacillus was present. 



The remainder of the survivors were injected with a virulent 

 culture and all died within a few hours. 



The following table shows the increase of the virulence of 

 the organism. The first lot in the series was inoculated with 

 Dr. d'Herelle's culture, the others were each inoculated with a 

 suspension of the intestinal contents of the preceding lot. 



TABLE I. 



SHOWING THE INCREASE IN THE VIRULENCE OF C. acridiorum, TEMPERATURE ABOUT 85°F 



*Did not all die. 



tNo observation made until 15 hours after injection. 



JNo observation made between the 10th and 19th hours after inoculation. 

 The temperature on the day this lot was inoculated fell nearly 10°F., which 

 accounts for the longer time required for death to occur. 



