June, '34] burnside : bacteria associated with European foulbrood 659 



rods were present in small numbers (Plate 6, C). Thus it is apparent 

 that the morphological forms encountered in sick larvae present a com- 

 plex and variable picture. 



When bacterial growth occurred after death of larvae, it usually con- 

 sisted almost entirely of moderate-sized rods, of which a variable per- 

 centage formed spores of B. alvei. (Plate 6, D.) Occasionally coccoid 

 bacilli indistinguishable morphologically from bacilli that grow in the di- 

 gestive tract of sick larvae caused decay of the body tissues after death. 

 In still other larvae decay was caused by both the rod and the coccoid 

 form. 



Cultures from Sick or Dead Brood Yielded Different Morph- 

 ological Forms. — Rough inoculation of bouillon agar slants from sick 

 or dead brood most frequently yielded cultures of B. alvei which sporu- 

 lated promptly. Many cultures, particularly those prepared from the 

 digestive tract of larvae in an early stage of infection, yielded a coccoid 

 organism in apparently pure culture which morphologically and cul- 

 turally closely resembled 5". apis, and there seems to be little doubt that 

 it is identical with the form described by Maassen (P) in 1908 and later 

 studied by White (^11, 12, 13), Wharton {14), and Lochhead (5). On 

 egg-yolk agar many cells of this form become lancet-shaped and were 



of the cells are still dividing; the majority are coccoid with rounded ends, while 

 some are more or less pointed. In B the coccoid cells, short rods, and medium 

 long rods are about equally numerous. In C most of the cells have pointed ends 

 and are typical of the type known as Bacillus pluton; two long, slender rods, such 

 as occur in small numbers in infected larvae, are also seen. 



D, Spores of Bacillus alvei from the decayed remains of a larva dead of European 

 foulbrood. 



E, Pure culture of Streptococcus apis from agar culture containing unheated egg 

 yolk. In some cultures 50 per cent or more of the cells become more or less 

 pointed and are indistinguishable morphologically from Bacillus pluton. 



F, Bacillus alvei and Streptococcus apis from an agar culture prepared directly 

 from a sick larva. (2 days at 36° C.) 



G, Streptococcus apis from a culture prepared directly from a sick larva in brood 

 filtrate. (2 days at 36° C.) 



H, Asporogenic agar culture of Bacillus alvei, which morphologically closely 

 resembles Bacterium eurydice. (5 days at 20° C.) 



/, Threadlike rods from an asporogenic agar culture of Bacillus alvei. (17 days 

 at 20° C.) 



/, Rods from an asporogenic bouiUon-agar culture of Bacillus alvei with beaded 

 and granular protoplasm. (S days at 36° C.) 



K, Culture of Streptococcus apis in bouillon broth, showing rods of B. alvei 

 which appeared after 6 days at 36° C. 



L, Pure culture of Streptococcus apis from bouillon agar to which 10 per cent 

 honey was added. (,36° C.) 



