Bacilhis ahei. By Messrs. F. Cheshire tf: Wafso)i Cheyne. 593 



them over tlie cell, press down the cover-glass so as to diffuse the 

 vaseline around its edge, and place the slides in an incubator kept at 

 the temperature of the body. These slides are removed at different 

 intervals of time, and as soon as each is taken out the cover-glass 

 is turned over and the drop of fluid rapidly dried. The specimen 

 can then be stained, mounted in Canada balsam, and studied at 

 leisure. This method seems to me to be much more satisfactory 

 than the observation of the organisms swimming about in the drop 

 of fluid, while the specimens can be kept permanently and comi)ared 

 with one another. 



In order to study the growth of the spores I used a cultivation 

 on the agar-agar cultivating material which had been kept at the 

 temperature of the body for fourteen days, and which consisted 

 almost entirely of spores, though a few bacilli were present. As 

 the result of several experiments, I have got a series of preparations 

 which have been taken at various times (15 min., 30 min., 40 min,, 

 1 hour, 1^ hour, 1 hour 50 min., 2 hours, 2 hours 20 min., 2 hours 

 50 min., 2 hours 55 min., 3 hours 20 min., 4 hours 20 min., 

 5 hours, 5 hours 35 min., 5 hours 40 min., and 7 hours 50 min.), 

 and the course of events is shown in plate X. The bacilli stain 

 with various anilin dyes — best, I think, with methyl- violet ; but 

 the spores resemble the spores of other bacteria in not taking on 

 the stain. The cover- glasses on which the organisms are dried are 

 passed three times through the gas flame and floated on. the sur- 

 face of a fairly strong watery solution of methyl-violet for one to 

 two hours. They are then washed in water, and afterwards laid in 

 weak acetic acid (1 per cent.) till no more stain comes out. They 

 are again washed in water, allowed to dry at the ordinary tem- 

 perature, and mounted in Canada balsam. A spore-bearing culti- 

 vation shows the bacilli stained violet, and the spores unstained, 

 with the exception of their outline, which is of a faint violet 

 colour. In most cases no trace of the rod in which the spore was 

 formed can be seen (see fig. 7). The first change which is 

 observed on cultivation is that in many cases the outline of the rod 

 in which the spore was formed becomes faintly visible (see fig. 7). 

 This can be seen in fifteen minutes, and is, I think, simply due to 

 swelling by the fluid, as it is also evident to some extent in the case 

 of spores soaked in water for the same length of time. In from 

 half an hour to an hour it is evident that the bacilli which were 

 present in the original material are beginning to multiply, and a 

 considerable number of rods are now seen containing spores. 

 It is evident that these spores are newly formed, as extremely 

 few bacilli containing spores were seen in the original material, 

 whereas in the preparations taken from in half an hour to an 

 hour a considerable number are present. That some of the rods, 

 instead of growing by fission, at once proceed to form spores 



