1918] Coccobacilliis Acridioriim D'llerelle 27 



Experiments with Bacillus poncei. 



On reviewing the tables which illustrate my experiments 

 with B. poncei and the other bacteria investigators in this 

 subject may wonder why I used females more often in preference 

 to males. The reasons are these: Female grasshoppers are 

 much larger than the males and consequently easier to handle. 

 Moreover, they seem to be hardier and withstand the alcohol 

 bath and hypodermic needle much better than the males. 

 Finally, the females naturally live longer which is, of course, a 

 decided advantage in any experiment. 



Another inconsistency in my experiments seems evident 

 from the fact that at times I used a smaller or a larger number 

 of animals in one experiment than in another. This was found 

 necessary for the reason that large numbers of female grass- 

 hoppers of the desired species, sufficiently mature for exper- 

 imentation, were sometimes difficult to find in the region where 

 my laboratory experiments were performed. 



The tables given on pages 38-41 are self-explanatory. 

 The insects were always inoculated with one drop (Ko c. c.) 

 of the particular fluid. The emulsion of the six months old 

 agar culture of B. poncei given in Table I was prepared by 

 adding 10 c. c. of sterile water to the old culture and shaking the 

 tube vigorously. The emulsions of the intestinal contents of 

 dead animals were prepared by dissecting out the intestines 

 under aseptic conditions and triturating in sterile test tubes 

 containing 5 c. c. of sterile water. This material, owing to the 

 fact that it contained shreds of tissue was filtered in a sterile 

 filter especially prepared for the experiments and from which 

 unfiltered air was excluded. 



Tables II, III and IV represent passage infections modeled 

 after the experiments performed by other workers. By an 

 examination of Tables I-IV it would seem that I had increased 

 the virulence of B. poncei, while the deaths represented on 

 Tables I and II extend over a long period of time; at the second 

 and especially at the third passage Tables III and IV, the 

 number of days elapsing between infection and death are 

 considerably shortened. 



The optimist would at once proclaim this as evidence for 

 increase in virulence, but such is not the case. The three 

 animals dead in the last experiment were carefully examined 



