14 BULLETIN 810^ U. S, DEPARTMENT OE AGRICULTURE. 



cular and uniform in outline. The color is bluish by transmitted and grayish 

 by reflected light. Under a two-thirds objective they are a light brown, and are 

 finely granular near the periphery, but more coarsely granular near the 

 center. 



Morphology. — The rod (fig. 4; PI. VII, C) is small and slender with slightly 

 rounded ends, occurring usually in pairs or singly. It is nonmotile and no 

 spores are produced. 



Staining properties. — It is stained easily and uniformly with the ordinary 

 aniline stains and is Gram-negative. 



Oxygen requrenvents — Growth is better in the presence of air than in anaero- 

 bic conditions. 



Bouillon. — Growth takes place slowly, producing a uniform cloudiness with 

 no pellicle. After a week or more a somewhat viscid sediment is present. 



Sugars. — Growth in the sugar media is slow, variable, and never luxuriant. 

 Both arms may be clouded. Glucose or levulose when added improves a 

 medium. Fermentation with gas does not take place in any of the sugars. 

 A noticeable amount of acid is formed when glucose and levulose are used, 

 the other sugars being less affected. A 1 per cent honey solution supports 

 a moderate growth. Brood filtrate as a rule improves media. 



Milk. — In plain and litmus milk no changes are visible. 



Potato.— Growth on potato is slow. When present, the culture is for the most 

 part grayish in color. 



Gelatin stab. — A bluish gray growth appears slowly along the line of inocula- 

 tion. No liquefaction follows. 



Pathogenesis. — No ill results are ob- 

 served when cultures of Bacterium eury- 

 dice are fed to healthy colonies of bees. 

 A rabbit inoculated subcutaneously with 

 a pure culture proved to be refractory. 



BACILLUS OKPHEUS 



The name Bacillus orpheiMS was 

 given to an interesting species occa- 

 sionally encountered in European 

 foulbrood (15). In one instance 

 the species was found very widely 

 distributed in an apiary in which 

 FIG. 5.— Bacillus orpheus: Spore for- heavy losses Were being sustained 

 mation. from the disease. In this case the 



dead larvse when dry were stonelike in character, the petrified re- 

 mains breaking like so much marble. Usually the species is met with 

 in a less number of the affected larvae. It can be readily identified 

 from its morphology and cultural characteristics. A description of 

 the species has been made by McCray (9). An organism similar to 

 B. orpheus in many respects has been described by Laubach (5) and 

 named Bacillus laterosporus. 



The organism is a motile spore-bearing rod with a few peritrichic flagella. 

 Spore formation begins in a few hours on the surface of the agar at incubator 

 temperature, the rod swelling toward the center and becoming fusiform. Soon, 

 as determined from stained preparations, the spore is seen occupying one side 



