Journal of Agricultural Research 
Vol. VIII, No. ii 
400 
cultures studied 
* 
Source. —The cultures studied are obtained in the course of the daily 
examination of specimens of suspected brood and comb. Cultures can 
nearly always be obtained by adding bits of comb from any source to the 
melted agar of petri dishes at pouring. The organisms occur also vari¬ 
ously distributed about the hive and can be secured from scrapings of hive 
covers, bottoms, and walls. They are also found occasionally in con¬ 
siderable numbers in some larvae, as manifested by the goodly number 
of colonies occurring on agar plates after the contents of a broken-up 
larva have been added. Over 30 strains isolated from comb and brood 
from the various sections of the United States have been cultured and 
studied. For comparison, one culture of B . vulgatus was obtained from 
the Bureau of Animal Industry and one culture was isolated from potato. 
Age OE cultures studied. —The cultures were studied at all ages, 
from the earliest date at which it is possible to isolate pure cultures and 
inoculate them into the various culture media up to over years. 
The rejuvenation of cultures after the method of Fuller and Johnson (4) 
was found valuable in obtaining constancy of cultural characteristics. 
Variation. —From the foregoing statements concerning the age and 
number of cultures studied, it can be seen that abundant opportunity was 
afforded for observation, first, of the variation in the same strain due to 
environmental factors acting over a considerable period of time, and, 
second, of*the variation as exhibited in a number of different strains of 
the same species. Variation due to both of these factors proved to be 
considerable, but there is no reason to believe that it is of any greater 
degree for these organisms than for many other bacterial species (1,5, 
6,9,11,15). 
Of the organisms of the B. vulgatus group isolated and studied, it seems 
best for the present to place all under two species only. Most of the 
organisms isolated are to be classed as B . vulgatus; a much smaller number 
belong to the species B . mesentericus . It is realized that further studies 
may show such great permanent differences in biology as to warrant a 
separation into still other species, especially of some of the organisms 
described as B . vulgatus . There is, however, one variety from sample of 
brood 2329 1 which presents such differences in cultural features that it 
is regarded as at least a special variety of B. vulgatus , if not a distinct 
species. This variety is described later in this paper. 
media USED 
Reaction. —All media are made 1.5 per cent acid to phenolphthalein, 
unless otherwise stated (3). 
1 In the original notes all cultures, as the above, are designated by a number, and this number refers to 
the sample sent to the Bureau of Entomology for diagnosis, from which the organism was originally isolated. 
By referring to the card on file for such sample, various data concerning the original source of the culture 
are available. 
