Mar. 12,1917 
Spore-Forming Bacteria of the Apiary 
405 
the use of these thin tubes, the spore suspension acquires the tempera¬ 
ture of the water bath almost immediately. In testing B . vulgatus and 
B. mesentericus for the thermal death point, spores of varying age were 
used. In the earlier experiments, where the heatings were made for 
10 minutes at temperatures of 90° C. and under, no record was made 
of the age of the spores. In these early experiments heating at 90° for 
10 minutes did not kill the spores, as a growth was secured in the tubes 
of spore suspension after heating and on agar plates made from 
the tubes. In the later experiments, cultures of various strains of B. 
vulgatus and B. mesentericus on potato and agar slopes about 1 month 
old were used. In such cultures there are practically only spores, and 
it is likely that at this age they have lost little of their vitality. The 
greatest amount of heat applied was ioo° C. for 20 minutes, with the 
result that growth occurred in some of the tubes containing spore sus¬ 
pensions of B . vulgatus and on agar plates made from the tubes. 
B . mesentericus seems not to survive the amount of heat that some of the 
strains of £. vulgatus do. Beyond these statements the writer does not 
wish to commit himself. It is believed that much careful work, with 
spores of known age from different strains on different culture media, and 
secured under different conditions of growth and development, will be 
necessary to establish the maximum amount of heat required to kill 
the spores of the organisms studied. 
Bacillus mesentericus (Flugge), Lehmann and Neumann (8), Chester (2) 
Syn. Bacillus mesentericus fuscus Flugge. 
Occurrence. —Found everywhere about the apiary, on combs, and on 
different parts of the hive. Found on culturing larvae, both diseased and 
healthy. 
Morphology and micrometry. —Hanging-drop and hanging-agar-block 
cultures show a finely granular organism occurring in ones and twos and 
short chains of a dozen or so individuals. Rarely coarse metachromatic 
granules may be seen. The flagella are distributed over the body. The 
rods are smaller than those of B. vulgatus , measuring from 1.3 to 2.8 ju 
in length and from 0.4 to 0.8 ix in width. The average length, however, 
lies nearer the mean of the extreme lengths observed above. Spores 
are usually formed in the middle of the rod, but may be found nearer 
one end. They measure from 1.0 to 1.9 ju in length and from 0.5 to 0.8 
in width. 
Motility.— The organism is actively motile. 
Gram’s stain. —It appears that the organism takes Gram’s stain only 
partially. 
Oxygen requirements. —Aerobic and facultatively anaerobic, proba¬ 
bly growing better at the surface of the deep glucose-agar tube than 
throughout the medium. 
Agar colonies. —The colonies at the surface are circular and usually 
smaller than those of B . vulgatus , although they may spread over the 
