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The number of these rod-shaped micro-organisms found in different film pre- parations varies considerably. Films prepared from the spleen and hæmorrhagic, lymphatic glands usually contain considerable numbers of the micro-organism. The number of those present in the blood is small.
The morphological appearance of the micro-organism varies considerably according to the conditions under which it lives. As already mentioned it may be like a coccus or become biscuit-shaped. In other cases it may become distinctly longer and thicker so that no difficulty is experienced in determining its bacillary or rod-shaped outline. In cultures, particularly in bouillon, there appears to exist a tendency on the part of the organism to elongate into threads. The micro- organism does not appear to possess a definite capsule.
Motility.
In no strain of this micro-organism so far isolated, has any trace of motility been observed. So far as can be made out, the organism is possessed of no cilia.
Tinctorial Reactions.
All the ordinary aniline dyes stain the micro-organism readily. If there is any preference perhaps carbol-fuchsin and gentian violet give the clearest pictures. The bipolar appearance is most clearly seen after treatment with carbol-fuchsin and half per cent. acetic acid.
The micro-organism does not retain the colour when treated by GRAM'S method of staining. This is constant in all strains of the organism so far met with.
Relation to Oxygen.
The micro-organism is a facultative anærobe.
Optimum Temperature.
It grows most luxuriantly at the aminal body temperature.
Cultural Characteristics.—Gelatine Plates,
To the naked eye the colonies appear after 48 hours as minute white points. These in the course of a few days increase in size and form definitely rounded colonies with somewhat irregular edges. They are semi-transparent, glistening, and of a whitish hyaline appearance.
With the aided eye, little more can be made out, excepting the roughly granular character of the growth.
Colonies of the micro-organism lying in the depth are smaller in size and more opaque.
Gelatine Strokes.
The growth forms a thin whitish coating. Its spread is extremely limited, the colonies tending to remain discrete.
Gelatine Stabs.
The
The growth is limited, but occurs throughout the extent of the line of inoculation. It is granular, whitish, and semi-transparent in appearance. growth is more abundant in the upper layers of the gelatine than in the under- lying portions. The surface of the gelatine becomes covered with a whitish hyaline layer which only under exceptional circumstances reaches the wall of the
tube.
It never liquefies gelatine.
Agar-agar Plates.
To the naked eye the colonies after 24 hours appear as rounded, structure- less, glistening, and semi-transparent bodies of a greyish white colour.
With the aide eye these colonies are found to possess sharply deinarcatel edges. Their substance is finely granular.
Deeply situated colonies are rounded with smooth edges. They are deeper in colour and present no appearance of granulation.