574 SUMMARY OF CURRENT RESEARCHES RELATING TO 



other hand, tended to pass spontaneously into the motile, especially on 

 media containing lactose. 



It had been necessary, therefore, for identification, to try to obtain as 

 many other stages of each life-history as was possible. The preferable 

 method would have been to have obtained the sporoblast as described 

 above, and then to have brought about the development from it of the 

 other phases. This method had to be given up for the time, owing to 

 the difficulty of getting the bacteria to grow at the required temperature. 

 It had been found, however, in the course of the experiments on the 

 modification of the macroscopic appearance of the cultures, that on heat- 

 ing the spores for longer than the time, which had apparently sufficed to 

 kill them, the bacillus sometimes reappeared. The spores were therefore 

 heated for still longer times and in various solutions, and other types of 

 microbe were occasionally obtained. Many of the sporing bacteria from 

 the blood and saprophytic bacteria were used as well as those from the 

 anthrax and tubercle bacilli. 



The suMilis spores from anthrax were got by heating a two-and-a 

 half -months old culture and from the subculture in lactose broth of a 

 five-months old culture, which grew a wrinkled film, the broth below 

 being clear and alkaline, while the other test broths gave typical cultures of 

 the anthrax bacillus. The temperature for transforming the spores was, 

 as a rule, 110°, the heating medium salt solution with or without alkali, 

 and the time, for anthrax, at most five minutes. Slight variations in the 

 process and even in the age of the spores used' often affected the result 

 materially. At best, 10 p.c. of the subcultures on one medium or 

 another gave positive results (agar with various sugars was used). The 

 microbes obtained included four apparently different staphylococci. A 

 pink coccus, shown under the Microscope, could be seen to transform 

 itself directly into a bacillus on certain media, especially glucose-agar, 

 reverting to the coccal form when put back on plain agar. It was 

 possible that such direct transformations were comparatively frequent. 

 A diphtheroid and various - coccobacilli and diplobacilli were also got. 

 Of the tubercle bacillus both human and bovine types, and the Arloing- 

 Courment bacillus were used. It required a good deal of care to get 

 positive results. The temperature was 41^°. The human bacillus 

 turned five times out of six in ^ c.cm. alkaline*broth and the six thtime 

 in 1 c.cm. The bovine turned in the 1 c.cm., and the Arloing-Courment 

 in the 1 c.cm. and 3 c.cm. broths. Often a bacillus which gave negative 

 results would give positive if tried a week or so later. Parallel cultures 

 from different media such as egg and glycerin agar would also give 

 different results. 



The sporing bacteria corresponding to the tubercle bacilli differed 

 from all those hitherto worked with in being more readily killed by heat. 

 Five minutes boiling sufficed when first obtained, whereas most resisted 

 for one and a half hours, the anthrax ones for over an hour, and one from 

 a rheumatic blood for about six hours. Their upper limit of growth and 

 spore formation were, when first got, about 10° higher than those of the 

 subtilis type from anthrax. 



The microbes got from overheating these tubercle spores were chiefly 

 cocci. The temperature used was not higher than 105° for two to five 



