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Journal of Agricultural Research 
Vol. VIII, No. ii 
colonies of B. mesentericus (PI. 93, A) present a finely granular or stip¬ 
pled appearance. 
(c) B . alvei and B . orpheus both grow slowly on potato; often it is 
almost impossible to detect any growth at all by the naked eye (PI. 94, 
C, D), but stained smears must be made from the slope (fig. 3). 
(d) The microscopic appearance of stained smears in the spore stage 
should be an important differential aid. Spores of B. alvei almost invari¬ 
ably show a vestige of the rod remaining (fig. 4); this does not occur in 
B. vulgatus (fig. 2), B. mesentericus (fig. 1), or B. larvae (fig. 5). The spores 
of B. orpheus (fig. 3) are distinctive, being excentrically placed. 
Fig. 2.—Bacillus vulgatus: Smear from a 9-day-old agar culture. X 1,480. The rods are morer regular 
in younger cultures. 
(e) B. larvae does not grow on the ordinary media of the laboratory, 
but requires media prepared from the juices of bee larvae. 
(/) Inasmuch as B . pluton occurs constantly and in such large numbers 
in European foulbrood larvae, it was thought well to include a drawing of 
the organism (fig. 6). 
PART II.—INOCULATION EXPERIMENTS 
In the inoculation experiments not only the definitely different and 
typical species of B. vulgatus and B . mesentericus were used but also 
those atypical strains not partaking so strictly of specific biological 
characteristics. As will be seen from Table I, the inoculations include 
