WHITE, JULY 29, 1907. 81 



The way by which this difficulty is overcome is reported in the pub- 

 lication under consideration. Young pupas were used in making the 

 medium. These were picked from a comb containing healthy brood, 

 cruslied, strained through cheesecloth, and then diluted by adding 

 water equal to from 20 to 50 times the volume of the crushed brood 

 used. This solution was then passed through ordinary filter paper 

 and subsequently through a Berkefeld filter. In this way a sterile 

 filtrate was obtained. About 2 c. c. of the sterile fdtrate was then 

 added by means of a sterile pipette to liquefied agar which had been 

 cooled to 45° or 50° C, If pure cultures were desired, agar tubes 

 thus prepared were inoculated with a small amount of diseased brood 

 and plates were poured. If, however, culture growth was desired 

 for the inoculation of bees or experimental animals, it was obtained 

 from these specially prepared agar tubes by first inclining them 

 and then securing the growth by inoculating the surface of the 

 inclined agar with a pure culture of Bacillus larvse, obtained from the 

 plates. At no time was this special medium to reach a high temper- 

 ature. 



Two colonies were now fed the scales of American foul brood, 

 suspended in sirup. American foul brood resulted from these inoc- 

 ulations with symptoms the same as are found in an apiary in which 

 the disease appeared through the natural means of infection. 

 Similar results were reported by Erne (p. 76). These expermients 

 were sufficient to prove that American foul brood can be produced 

 experimentally by feeding; also, that the scales of the disease 

 contained the virus. 



Having demonstrated the fact that American foul brood can be 

 produced by feeding and having obtained pure cultures of Bacillus 

 larvse, in suitable form for inoculation purposes, the next step to be 

 taken, very naturally, was to inoculate healthy colonies with pure 

 cultures of Bacillus larvse. This was now done, and as a result of 

 such inoculations American foul brood was produced with symptoms 

 identical mth those produced when the scales were used in feeding. 

 The decaying brood in the disease thus produced contained the large 

 number of spores that are always found in brood dead of this disease, 

 and from the diseased material pure cultures of Bacillus larvse were 

 obtained. 



The results obtained from these experiments in which pure cul- 

 tures of Bacillus larvse were used in making the inoculations justified 

 for the first time the statement that American foul brood was caused 

 by a specific microorganism. 



It seemed to the author of the circular that probably the species 

 which had given different workers considerable difficulty in culti- 

 vation, in many cases at least, was nothing other than Bacillus 

 13140°— Bull. 98—12 6 



