AMERICAN FOULBROOD. 13 



terized by ropiness and foul odor — European foulbrood. These 

 observations taught, therefore, that B. alvei was not to be associated 

 with American foulbrood — the ropy, foul-smelling disease — but with 

 European foulbrood, which does not possess these characteristics. 



After beekeepers had convinced themselves that there were two 

 foulbroods, one with a peculiar foul odor and showing a marked 

 ropiness of the dead brood and the other without these characters, 

 B. alvei unfortunately remained in the literature as the cause of 

 the ropy, foul-smelling disease. This fact accounts for not a little 

 of the confusion that has existed in connection with the brood 

 diseases. It should be remembered that B. alvei is not the exciting 

 cause of any bee disease. 



The writer found (20) that the spores which had refused to ger- 

 minate on the media ordinarily used in the laboratory would germi- 

 nate and the bacillus would grow in an agar medium in the prepara- 

 tion of which bee larvae were used. Satisfactory cultures for experi- 

 mental purposes were not obtained with this medium, however. 

 Later he (23) succeeded in devising a medium (p. 18) by the use of 

 which pure cultures of Bacillus larvae suitable for experimental work 

 could be obtained in abundance and with such cultures American 

 foulbrood was produced by inoculation, the experimentally produced 

 disease manifesting symptoms that are typical of American foul- 

 brood encountered in nature. 



BACILLUS LARVAE 



Bacillus larvae, the cause of American foulbrood, had been seen by microscopists 

 doubtless long before it was cultivated successfully in the laboratory. The species 

 requires special media for its cultivation. Success in the germination of its spores 

 was attained in 1903 on an agar made from bee larvae. Pending more definite 

 information regarding the bacillus the writer (20) referred to it by the term, Bacillus 

 "X." Further knowledge concerning the species was gained during the summer 

 of 1904, and it was given the name Bacillus larvae (White 21, 22). Bund (6) in Swit- 

 zerland, working on the disease entirely independently, also recognized the fact 

 that the spores present in such large numbers in the scales represented a new species 

 that was difficult of cultivation. Maassen (14) has referred to the species as Bacillus 

 brandenburgiensis, and Cowan (10) has referred to it as Bacillus burrii (8). 



Occurrence. — Bacillus larvae occurs in the brood of bees dead of American foulbrood 

 and where contaminations with such material have taken place. 



Morphology. — The vegetative form is a slender rod with ends slightly rounded 

 and with a tendency to grow in chains (fig. 1; PL VII, A). It varies markedly in 

 length, depending largely upon the medium used in its cultivation. On the surface 

 of brood-filtrate agar it is more often from 2.5 to 5 p in length and about 0.5 n in 

 breadth. In a liquid medium it is usually much longer, becoming then frequently 

 filamentous in character. During the vegetative stage the bacillus undergoes changes 

 (fig. 5; PI. VII, E, F, G, H) seldom noted for the bacteria. The rod possesses numerous 

 flagella which are peritrichic in arrangement (fig. 2; PI. VII, C). 



Giant whips. — Giant whips occur (fig. 6; PI. VII, F, G, H)in large numbers, being 

 found especially numerous in the water of condensation of brood-filtrate agar cultures. 

 These corkscrewlike structures vary widely in their dimensions from scarcely visible 

 coiled filaments to bodies several micra in diameter. 



