THE PRESENT INVESTIGATION OF AMERICAN FOUL BROOD. 



41 



darker, resembling roasted coffee in color. Usually the larvse are attacked at 

 about the time of capping, and most of the cells containing infected larva^ are 

 capped. As decay proceeds these cappings become sunken and perforated, and, 

 as the healthy brood emerges, the comb shows the scattered cells containing 

 larva? which have died of disease still capped. The most noticeable charac- 

 teristic of this infection is the fact that when a small stick is inserted in a 

 larva which has ilied of the disease, and slowly removed, the broken-down 

 tissues adhere to it and will often stretch out for several inches before break- 

 ing. When the larva dries it forms a tightly adhering scale of very dark 

 brown color, which can best be observed when the comb is held so that a bright 

 light strikes the lower side wall. Decaying larv;e which have died of this disease 

 have a very characteristic odor, which resembles a poor quality of glue. This 

 disease seldom attacks drone or queen larva\ It appears to be much more 

 virulent in the western part of the United States than in the East. 



A iiiieroscopic preparation from the diseased, but not dead larvse, 

 or from larva^ recently dead, at first sliows a fev^' comparatively long 

 slender rods; later these increase rapidly in number, and spores also 

 are seen. In the later stages of decay in the ropy mass and the dried 

 scales spores only are found; these occur in very large numbers. 

 When this investigation v;as begun, in 1002, it was observed (20) 

 that in the dried dead larva^ there are very large numbers of spores, 

 but these, when inoculated into the media commonly used in the 

 laboratory, fail to grow. The cultures were sterile, except for an oc- 

 casional contamination. 



The Present Investigation. 



The following samples from diHerent sources were examined in 

 1902: 



Results of exam illation of specimens of American foul brood diac/nosed by the 

 experts at that time siinpli/ as ''foul brood." 



Inasmuch as Bacillus alvei was absent, it is evident that this condi- 

 tion is not European foul brood (20). 



In 1003 the investigations were continued. Several media were 

 devised in which it was hoped that it would be possible to obtain a 

 germination of the spores which were observed the j^ear before and 

 which failed to grow on our ordinary media. The one which proved 

 successful was prepared as follows : Larva? are picked from the brood 

 combs of a number of frames of healthy brood and a bouillon (bee- 

 larvse bouillon) is made from them following the same directions as 

 when bouillon is made from meat. Our first growth from these 



