Bacterial Disease of the Squash-bug. 



365 



The above results and a few others are briefly indi- 

 cated in the table below. 



Table VI. 



Parallel with the above, I also tested a bacillus iso- 

 lated from the tissues of a diseased grasshopper out of 

 the lot from Colorado. Two beetles were used. Oue of 

 these remained healthy for several hoars, and no further 

 observations were made. The other was kept in the in- 

 fusion for a much longer period, and at the end of sev- 

 enteen hours it was still living, though quite sluggish. 

 In a few hours more death ensued. 



A comparison of these two groups of tests gives abund- 

 ant evidence that the squash-bug bacillus produces by 

 its growth some toxic compound which acts with con- 

 siderable rapidity even on hard-shelled insects. It is well 

 known that many bacteria produce by their growth or- 

 ganic compounds of one kind or another, and it is well 

 to mention in this connection that while a water-beetle 

 will live for more than a day in fresh bouillon, death 

 occurs in a few hours if the bouillon has "gone bad," 

 although it may be subsequently sterilized. The prod- 

 ucts of such decomposition are thus to a slight degree 

 deleterious to the water-beetle. 



In the above table the record of experiments seems to 

 indicate that the isolation culture was slightly more effec- 



