12 BULLETIN 810, U. S. DEPARTMENT OF AGRICULTURE. 
seems quite probable that the disease might in some cases be carried 
over for months or even over winter through the medium of these 
rubberlike scales. 
It is of interest to know that the amount of disease resulting imme- 
diately from inoculations in which scale material is used is much less 
than when larve recently dead of the disease are used. This is true 
also of dead larve stored in Petri dishes compared with smears allowed 
to dry immediately from larvee recently dead of the disease. These 
facts indicate a possible deleterious effect on Bacillus pluton of the sec- 
ondary invaders multiplying in the decaying larve. 
STREPTOCOCCUS APIS 
It is most probable that Streptococcus apis is the species that was 
isolated from diseased brood by Burri (3) and referred to by him 
in 1906 as “ giuntheri-forms.” Maas- 
sen described it in 1908 (8). The 
organism grows well at incubator, 
room, and refrigerator tempera- 
tures in most of the media ordi- 
narily used in the laboratory. 
Its cultural characteristics suggest 
the micrococci rather than the 
streptococci. Confusion in some 
of the earlier investigations was 
due evidently to the resemblance 
of Streptococcus apis and Bacillus . 
pluton morphologically. To this 
fact is due the chief interest in the 
species Streptococcus apis. When 
encountered in larve dead of European foulbrood it can be identified 
readily by culturing. The generic position of this species should be 
considered as being not altogether certain. 
Occurrence.—Streptococcus apis is occasionally encountered in larvz dead of 
European foulbrood and often is present in large numbers. 
Morphology.—It is more or less spherical (fig. 3; Pl. VII, E), occurring singly 
and in pairs with occasionally a chain of 2 or more pairs when grown in liquid 
media. In larval remains not infrequently the ends may be somewhat pointed. 
Staining properties.—It colors uniformly and readily with the common stains, 
and retains the stain after Gram’s method. 
Glucose agar plate-—Within a day growth is visible. Colonies never become 
large. Surface colonies are usually less than 2 mm. They are circular with 
uniform outline and a well-defined border, are grayish by reflected and bluish 
by transmitted light, are smooth and convex, are moist and glistening in ap- 
pearance, and are friable in consistency. When magnified the surface colonies 
appear light brown in color, and granular in structure, the density decreasing 
from the center to the periphery. Deep colonies appear dense, dark brown, and 
coarsely granular. They are in general lenticular to oval but are sometimes 
almost spherical in form. 
Fic. 3.—Streptococcus apis. 
