Bacillus ahei. By Messrs. F. Chesliire & Watson Cheyne. 595 



(tigs. 7 and 8). It seems to me that the view that spore-formation 

 occurs when the food is getting exhausted is correct, for the time at 

 which this appearance is found depends greatly on the size of the 

 drop placed on the cover-glasses, and I have found in one experiment 

 that in one specimen after twenty-three hours most of the rods 

 ■were forming spores, while in another specimen where the drop 

 was much larger there was no trace of spore-formation after twenty- 

 eight hours. I have here described the results of my earlier and 

 rougher attempts to study the formation of spores. I have, how- 

 ever, now improved the method in the following way. As I have 

 just now shown, the period at which spores are first seen seems to 

 depend mainly on the amount of fluid used and the number of 

 of bacilli introduced, and as in the above method both these factors 

 vary in each case, one cannot get a regular series of preparations 

 showing the different stages at different times. In studying the 

 sprouting of spores the amount of fluid and the number of spores 

 does not matter, for if sufficient nutriment is present and a proper 

 temperature maintained the spores must sprout, and probably they 

 always take about the same length of time. The difficulty of obtaining 

 a series of specimens illustrating spore-formation is easily obviated 

 in the following manner. Take a pure flask containing a small 

 quantity of sterilized infusion, and inoculate it from a cultivation 

 containing only bacilh. Place it in the incubator for two or three 

 hours, so that the bacilli may increase somewhat in number and 

 diffuse themselves through the hquid. Thus the cultivating mate- 

 rial contains bacilli pretty equally diffused through it, and if after 

 shaking the flask drops of equal size are taken, each will probably 

 contain about the same number of baciUi. The minutest quantity 

 of fluid can easily be obtained by means of a syringe having a fine 

 screw on its piston and a large nut revolving on this screw. The 

 circumference of the nut being equally divided into a number of 

 small segments, the same quantity of fluid can always be expelled 

 from the syringe. By proceeding in this way equal sized drops 

 containing an equal number of bacilh can be used and a regular 

 series of specimens obtained. I have found that using 2/5 of a 

 minim containing one bacillus and keeping the specimen at SS"^ C, 

 the earliest appearance of spore-formation was evident in forty-one 

 hours. 



Leaving these matters, which are of great interest not only in 

 regard to the Bacillus ahei, but to all spore-bearing bacteria, and 

 which I have therefore dwelt on at length, we must pass on to tho 

 further consideration of this particular organism. The first point 

 to be determined in investigating its relation to foul brood ^ya^ 

 whether this was a new bacillus, unknown except in connection 

 with this disease of bees, or whether it was a more or less well- 

 known form. To ascertain this point with regard to micro- 



