June, '34] burnside : bacteria associated with European foulbrood 661 



without having found or obtained B. alvei or 6". apis in culture, except 

 on rare occasions when mixed infection was suspected. Lilcewise cul- 

 tures prepared with honey and pollen from healthy colonies in which 

 European foulbrood never existed have never yielded B. alvei. 



The writer's observations on this point differ from those of Maassen 

 (P), who claims to have found B. alvei present in some cases in larvae 

 dead of "virulent foulbrood" (American foulbrood). In a few cases 

 the writer obtained B. alvei in cultures from combs infected with Amer- 

 ican foulbrood, but a thorough inspection of the brood xomb and of the 

 scales used in preparing the cultures generally revealed mixed infection 

 and occasionally a scale of European foulbrood which resembled that of 

 American foulbrood. It seems possible that Maassen may likewise have 

 been dealing with cases of mixed infection. 



Transmission of European Foulbrood with Cultures. — When 

 conditions are favorable, typical European foulbrood is readily trans- 

 mitted by inoculation with bacteria taken from the digestive tract of sick 

 or dead brood. On the other hand, typical European foulbrood has 

 only rarely been produced by inoculation with cultures, although several 

 investigators, in inoculation experiments with cultures of B. alvei 

 (rods and spores), have obtained an atypical infection. In the writer's 

 experiments an occasional larva or pupa was attacked by B. alvei when a 

 water suspension of sporulating cultures recently isolated from infected 

 brood was sprayed over developing brood. It appears that B. alvei in the 

 usual sporogenic state may, under favorable circumstances, produce 

 disease in larvae or pupae, but this disease is not typical European foul- 

 brood. 



Likewise, attempts to produce European foulbrood by inoculation with 

 pure cultures of 5". apis have usually been unsuccessful. Maassen (9) 

 failed to demonstrate pathogenesis for 6". apis by feeding pure cultures, 

 and White {12) states that "No disease results when the brood of bees 

 is fed cultures of Streptococcus apis either by the direct or indirect 

 method." In speaking of the coccoid form of B. alvei, Lochhead (d) 

 states, "Our attempts to produce the disease in a colony of black bees 

 through feeding cultures of the coccus have so far been inconclusive." 

 On the other hand, Wharton {14), in inoculation experiments with cul- 

 tures of a coccoid bacillus which Lochhead (5) says "appeared to be 

 closely related to, if not identical with. Streptococcus apis," claims to 

 have produced typical European foulbrood. Concerning this experiment 

 Wharton says, "The writer has obtained infection in a healthy colony of 

 black bees in four days, using as inoculum cultures of the organism de- 

 rived from isolated colonies. The symptoms of the diseased larvae 



