DIAGNOSIS OF BEE DISEASES. 7 



in abundance typical of either II. pluton or Strep, apis usually can be 

 found. In stained smears of /Strep, apis the organisms are found to 

 be spread out over the whole field with no tendency to grouping as in 

 the case of B. pluton. Sometimes in examining European foulbrood 

 larvae the microscopic picture shows practically nothing but B. pluton. 

 More often, however, Strep, apis, B. alvei, and other rod form.- :ir<- 

 found. Some larvae will disclose B. alvei alone, others Strep, apis 

 alone, and still others, these two organisms without B. pluton. ( Jon 

 tinued search is sometimes necessary before larvae are found reveal- 

 ing B. pluton, either alone or with one or more of the secondary 

 invaders just mentioned. The authors have found Bacillus pluton in 

 the small yellow, gray, and brown scales as well as in the soft melting 

 larvae. They are not prepared, however, to state the length of time 

 that the organism persists in the dried state. Mention has been 

 made of larger scales of rubberlike consistency which occur only 

 occasionally and in small numbers in a given comb. Such scales 

 always yield microscopically Bacillus alvei in abundance, and usually 

 this organism alone. The microscopic appearance of B. alvei in the 

 spore stage is rather characteristic, the spores practically always 

 showing vestiges of the rods clinging to them. This aids in dif- 

 ferentiating it from B. vulgatus and B. mesentericus. Bacillus 

 orpheus may be recognized microscopically in the spore stage by 

 the position of the spore in the rod, it being eccentrically placed. 

 Bacterium eurydice is a small, slender organism which does not 

 form spores. 



CULTURES. 



At the present writing no medium suitable for growing Bacillus 

 pluton has been devised, hence agar plates made from European 

 foulbrood larvae show only the secondarj 7 invaders — B. alvei, Strep. 

 apis, B. vulgatus, B. mesentericus, and B. orpheus. Bacillus alvei is 

 encountered very frequently and is always secured on culturing larvae 

 in which the microscopic examination has revealed the presence of the 

 organism. Streptococcus apis occurs occasionally. Bacillus vulga- 

 tus and B. mesentericus frequently are met, but usually in small 

 numbers only. Bacillus orpheus in large numbers is occasionally 

 encountered. Bacterium eurydice, as a rule, does not appear in the 

 cultures. Bacillus alvei is the only organism occurring with any 

 marked degree of frequency and in any great numbers on agar 

 plates made from affected larvae of any of the known infectious brood 

 diseases of bees. Rarely do cultures from larvae dead from any 

 cause other than European foulbrood show the presence of this 

 species. 



The appearance of B. alvei on agar plates is rather characteristic. 

 The colonies usually occur in abundance, often being innumerable. 



