. Pathogenic microörganisms; a practical manual for students, physicians, and health officers . anging-drop cultures, beforethe development of spores, appear to be homogeneous or nearly so; MORPHOLOGY 427 but in stained preparations they are seen to be composed of a seriesof rectangular, deeply stained segments. When obtained directly fromthe blood of an infected animal the free ends of the rods are slightlyrounded, but those coming in contact with one another are quite cultures the ends are seen to be a than the body of thecell and somewhat concave, giving the appear
. Pathogenic microörganisms; a practical manual for students, physicians, and health officers . anging-drop cultures, beforethe development of spores, appear to be homogeneous or nearly so; MORPHOLOGY 427 but in stained preparations they are seen to be composed of a seriesof rectangular, deeply stained segments. When obtained directly fromthe blood of an infected animal the free ends of the rods are slightlyrounded, but those coming in contact with one another are quite cultures the ends are seen to be a than the body of thecell and somewhat concave, giving the appearance of joints of one time much stress was laid upon these peculiarities as distinguishingmarks of the anthrax bacillus; but it has been found that they are theeffects of artificial cultivation and not necessarily characteristic of theorganism under all conditions. The bacillus is inclosed in a transparent-envelope or capsule, which in stained preparations (from albuminousmaterial) may be distinguished by its taking on a lighter stain than thedeeply stained rods which it Fig. 150.—Anthrax bacillus. X 900diameters. Agar culture. Fig. 151.—Spores heavily stained (inspecimen red). Bodies of disintegratingbacilli faintly stained (in specimen blue).X 1000 diameters. Spore Formation.—Under favorable conditions in cultures spores aredeveloped in the bacilli. These spores are elliptic in shape and about oneand a half times longer than broad. They first appear as small, refractivegranules distributed at regular intervals, one in each rod. As the sporedevelops the mother-cell becomes less and less distinct, until it disappearsaltogether, the complete oval spore being set free by its dissolution. (SeeFig. 151 and Plate III, Fig. 22). Irregular sporulation sometimes takesplace, and occasionally there is no spore formation, as in varieties ofnon-spore-bearing anthrax. Sporeless varieties have been produced artificially by cultivating thetypical anthrax bacillus
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