Contagious Diseases of Insects. 291 



viously from the fluids of a silkworm recently dead from jaun- 

 dice. Unfortunately, from some oversight, neither slides nor 

 detailed notes were made of this culture until the experiment 

 upon the cabbage worms was instituted. The beef broth, 

 nearly a gallon in quantity, contained in a large receiver, the 

 tube of which was closed with a sterilized cotton plug nearly 

 six inches in length, had promptly become turbid, as usual, and 

 was soon opaque with bacteria. By the 6th September the 

 development of the bacteria had apparently nearly ceased, a 

 thick deposit covering the bottom of the jar. The fluids at 

 this time contained vast numbers of spherical micrococci .7 /* to 

 .8 /* in diameter, mostly in doubles, apparently identical with 

 those occurring in the silkworm. The culture, however, which 

 had been several times opened for examination, was not at this 

 time wholly pure, but contained likewise bacteria and large and 

 small bacilli. These occurred, however, in relatively insignifi- 

 cant numbers, and the fluids when poured out presented no 

 odor of putrefaction, but had, on the contrary, only the faint 

 indescribable smell characteristic of the cultures of all our 

 insect bacteria. 



After infection on September 6. the cabbage worms were 

 fed with fresh food collected for them daily. Their cage was 

 kept in a large room, before an open south window, was 

 thoroughly cleaned each day, the paper covering the floor of 

 the cage being removed and burned, all the litter and debris 

 destroyed, and the larvae carefully transferred to fresh food 

 upon clean paper. 



A single individual died September 8, evidently from 

 accidental injury. Three of the larvae pupated on the 10th. 

 On the llth two died, apparently of disease. The fluids of 

 these were carefully examined and found to swarm with 

 micrococci. Of these covers were prepared in the usual form. 

 The first slide, made from the blood, contains large spherical 

 micrococci, nearly all in doubles, 1 p in diameter, excellently 

 stained with violet. The bacteria of the second slide, repre- 

 senting the contents of the alimentary canal, were more various 

 in form. In addition to the above large Micrococcus, 1 ^ in 

 diameter, many slightly double ovals of about the same trans- 

 verse diameter occurred, together with several .7 p. wide, most 



