Contagious Diseases of Insects. 305 



was opened. The fluid was covered with a rather thick til in 

 made up wholly of the above BaciUus intrapaUens.^ as deter- 

 mined at the time and as shown by beautifully stained and well- 

 mounted slides which I have studied recently. Many of these 

 were in long filaments, but none showed any sign whatever of 

 flagellate motion. This culture, like the preceding, was subse- 

 quently used for an infection experiment. 



Similar cultures from the same material were made April 

 21 and 24, three tubes being inoculated on the latter date. 

 From all these was obtained the same bacillar form, having 

 occasionally associated with it the sphericals already mentioned, 

 and in a single instance containing also a small Micrococcus 

 about .5 itt in diameter. 



The general results of these cultures unquestionably estab- 

 lish the possibility of preserving through several months the 

 bacterial form here dealt with, and afterwards cultivating it 

 successfully in beef broth. 



I have next to describe the infection experiments with this 

 Bacillus, showing the possibility of instituting disease in healthy 

 larvie by means of it, and of procuring its multiplication within 

 their bodies for some days subsequent to the infection. 



THE ZEBRA CATERPILLAR. 

 {Mamestra picta, Harris.) 



A small colony of zebra caterpillars found on cabbage near 

 Bloomington was brought to the Laboratory June 1, for infec- 

 tion experiments with one of the above cultures, — that begun 

 June 23 and found to contain the BaciUus intrapallens and 

 the spherical Micrococcus, as detailed above. A quantity 

 of this fluid was poured into a dish June 27, and a single 

 cabbage leaf was soaked in it for an hour and then fed to the 

 larvae. These ate freely of it, and were thereafter fed daily 

 with fresh cabbage and carefully attended, this first infection, 

 being the only one purposely made. A check lot of the same 

 brood was placed in a separate cage, but unfortunately removed 

 only a few yards from that infected. 



On the next day a single larva of the first lot was found 

 aluiost dead, and, being isolated, died during the night. 



