June, '34] burnside : bacteria associated with European foulbrood 663 



which infection was obtained three succeeding experiments gave negative 

 results. The results of this experiment and the comparable experiment 

 performed by Wharton (14) seem to point to retention of virulence by 

 5". apis during only about two generations on artificial culture media. It 

 is recognized, however, that the purity of such recently isolated cultures 

 may be questioned. 



Pleomorphism and Variability in Bacillus alvei. Several in- 

 vestigators have observed variation in size and shape of individual cells 

 in cultures of B. alvei. Maassen (P) says that cultures of B. alvei 

 degenerate on the usual artificial medium and that nuclei or granules 

 develop in the plasma while the ability to form spores disappears. Loch- 

 head (5, 6), using a special nutrient agar, observed the origin of coccoid 

 cells from rods of B. alvei, which he reported (6) to be indistinguishable 

 morphologically from B. pluton. 



In the writer's experiments B. alvei, in the form in which it is usually 

 isolated from dead brood, grew luxuriantly, spread rapidly over the 

 agar, and formed spores promptly and abundantly on bouillon agar and 

 on egg-yolk agar at 36° C. (Plate 7, A.) In repeated transfers at 36° 

 C. on these agars no morphological or cultural changes were observed. 

 In bouillon broth, potato broth, and milk, and in media containing sterile 

 filtrate prepared from honeybee larvae, the luxuriance of growth and the 

 tendency to form spores gradually decreased in repeated transfers. After 

 about 10 generations in potato broth, cultures prepared by rough trans- 

 fers to bouillon agar and egg-yolk agar grew slowly while "sporulation 

 was incomplete and delayed or lacking. Growth either spread slowly or 

 was confined to small colonies. (Plate?, S.) By planting and culturing 

 from isolated colonies, strictly asporogenic cultures were obtained which 

 in repeated transfers remained asporogenic. When cultured at room 

 temperature the transformation in potato broth from a sporogenic to an 

 asporogenic condition was more rapid. Bouillon broth seemed less 

 effective in producing the change, and results with filtrates from honey- 

 bee larvae were irregular. 



These asporogenic cultures of B. alvei varied in morphology and cul- 

 tural characteristics (Plate 6, H, I, J), but in some cases the resemblance 

 to cultures of asporogenic rods isolated by plating from sick larvae was 

 marked. It seems probable, therefore, that B. alvei may exist in infected 

 larvae in either sporogenic or asporogenic condition. 



Morphologically and culturally the characteristics of some of the cul- 

 tures were indistinguishable from the characteristics given by White 

 (11) for B. eurydice. (Plate 7, B; plate 6, H.) Concerning this form 

 White (13) says: "In studying this species cultures were isolated which 



