2 THE CAUSE OF EUROPEAN FOUL BROOD. 



similar in appearance, but clearly different from the one which Burri 

 had observed and Maassen had named. All attempts, however, to 

 cultivate this new species were unsuccessful. Until more was known 

 about this organism it was referred to in 1908 as " BaclUus Y.'"' 



In 1907 the writer demonstrated that American foul brood, an 

 infectious brood disease, could be produced by feeding to healthy 

 colonies pure cultures of Bacillus larva. This fact emphasized the 

 probability that if European foul brood is also caused by a bac- 

 terium this disease, too. could be produced by feeding pure cultures 

 of the bacterium causing it. 



To demonstrate this, it was desirable in the first place to determine 

 whether or not the virns of European foul brood was present and 

 active in the diseased brood. Healthy bees were fed sirup which 

 contained a suspension of the diseased brood, and European foul 

 brood was produced. This showed that the diseased brood did con- 

 tain the virus and that the disease could be produced by feeding. 

 This being done, pure cultures of Bacillus alvei isolated from the dis- 

 eased material were substituted for the diseased brood in the inocu- 

 lation experiment. Pure cultures of Streptococcus apis were isolated 

 and used likewise. Then cultures of Bacillus alrei and cultures of 

 Streptococcus apis were used simultaneously in making the inocula- 

 tions. European foul brood was not produced in any of the experi- 

 ments where pure cultures of either or both organisms were used. 

 These facts were sufficient to eliminate tentatively Bacillus, alvei and 

 Streptococcus apis from the list of possible causes of European foul 

 brood, and to justify a strong suspicion that the microorganism which 

 was referred to as " Bacillus Y " bore a causal relation to the disease. 

 It was necessary, however, to reckon Avith other factors before a 

 more definite statement could be made. 



A continuation of the work on the cause of European foul brood 

 has yielded some interesting results. These will be briefly con- 

 sidered in this preliminary paper. 



It has been observed in the examination of diseased brood that 

 Bacillus alvei is frequently either absent, or present only in small 

 numbers, in many of the larvse which seem from gross appearance to 

 be dead of European foul brood. Such samples have been received 

 as a rule from localities in which apparently the disease had only 

 recently appeared. Frequently, also. Streptococcus apis seemed to 

 be absent, or i^resent only in small numbers, in many of the larvae 

 which from gross appearance gave strong evidence of European foul 

 brood. These bacteriological findings further strengthened the 

 theory tliat neither Bacillus alvei nor Streptococcus apis is the pri- 

 mary exciting cause of European foul brood. Other inoculation 

 experiments were performed, using pure cultures of these two species. 



