Bacterial Disease of the /Squash-hug. 871 



Summarizing, tiien, it appears that this organism will 

 not survive at 125° F. a continuous exposure of two 

 hours, nor an exposure of one hour on more than one 

 day. At a temperature of 115° F. it will withstand an 

 exposure of one hour for several successive days, but no 

 continuous exposure of three hours or more. It survives 

 in great part an exposure of six hours at 105° F. on 

 four successive days, but with a continuous exposure 

 of four days at this temperature the organism is usually 

 killed. 



I have not yet had an opportunity to experiment with 

 this disease while keeping the bugs at different tempera- 

 tures; but such a line of work would be interesting to 

 supplement the above temperature tests, and to advance 

 our knowledge as to the relationship of conditions re- 

 quired by host and parasite. Neither have I yet deter- 

 mined precisely the range of optimum temperature for 

 this organism ; but such results as are recorded seem to 

 indicate that it is between 83° and 90° F. 



SPECIFIC CHAEACTERS. 



I have carefullv compared the biological characters of 

 this squash-bug organism with those enumerated for the 

 various entomogenous bacteria already described; but 

 there is no form with which it agrees in detail. Its ac- 

 tion on the insect and its characteristic pathogenic 

 properties seem, to be quite distinct ; hence I have given 

 to it the name Bacillus entomotoxicon, n. sp. 



This disease bacillus has also been carefully compared 

 with the organism "normal" to the coecal appendages 

 of the squash-bug. There is considerable structural dif- 

 ference, and the normal form is cultivated on nutrient 

 media with difficulty. I have secured cultures of the 

 latter on media strongly alkaline; but further details of 

 such work are not included in this paper, as the coecal 

 form is hardly to be confused with the disease organism. 



