38 KANSAS UNIVERSITY SCIENCE BULLETIN. 



lated, produce new races similar to*those of B. coli communis, 

 but of comparatively less stability. Judging from the B. coli 

 experiments, however, it is at least possible that by continued 

 selection of long threads one would finally obtain a variation 

 which would produce a permanent new race. In my cultures 

 of Bacillus typhosus there was a greater tendency to produce 

 long chains than in B. coli communis. As is well known, unse- 

 lected cultures of B typhosus are not uncommonly met with 

 which show a marked tendency to form long filaments, a 

 tendency partially dependent on the medium employed. For 

 instance, in some of my experiments B. typhosus showed a 

 marked tendency to form long filaments when grown on agar 

 containing malachite green in the proportion of 1 to 12,000. 

 On being transferred to broth, these cultures reverted to the 

 normal ; but the elongated tendency persisted to a slight 

 extent in the first broth culture. 



2. Bacillus megatherium {?). 

 From gum occurring in cane juice obtained from Louisiana 

 I isolated, in December, 1903, a large, plump, motile bacillus, 

 characterized by granular contents, and readily forming 

 spores. From cultures of this bacillus, probably B. mega- 

 therium, I made many attempts to obtain an asporogenous 

 race by selection. However large the proportion of cells 

 which form spores in hanging drops, there are usually some 

 few which remain motile and sporeless. Scores of those 

 sporeless cells were isolated and cultures obtained from them, 

 usually with negative results as regards obtaining races with 

 diminished spore-forming power. About March 1, 1904, a 

 single sporeless rod of this type was isolated, the offspring of 

 which remained sporeless, though cultivated under conditions 

 under which the type produced spores abundantly. Granules 

 somewhat resembling early stages of spore formation ap- 

 peared frequently in cells of this race, but no mature spores. 

 At various times during the two months following its origin, 

 this race was compared with the check in broth and on agar. 

 The check formed spores, while the race remained sporeless. 

 Cultures of the sporeless race, taken soon after its origin, 

 and of the check, were sealed in test-tubes. After one year 



