(navigation image)
Home American Libraries | Canadian Libraries | Universal Library | Community Texts | Project Gutenberg | Children's Library | Biodiversity Heritage Library | Additional Collections
Search: Advanced Search
Anonymous User (login or join us)
Upload
See other formats

Full text of "Pathogenic Bacteria"

DIPHTHERIA.

289

appearance. It must be remarked that when sudden
transplantations are made from blood-serum to agar-
agar the growth resulting is meagre, but the oftener
this growth is transplanted to fresh agar-agar the more
luxuriant it becomes.

The growth in gelatin puncture-cultures is character-
ized by small spherical colonies which develop along the
entire length of the needle-track. The gelatin is not
liquefied.

Upon the surface of gelatin plates the colonies that
develop do not attain anything like the size of the colo-
nies upon Loffler's mixture. They appear to the naked

FIG.  79.—Bacillus diphtherias, colony twenty-four hours old upon agar-agar;
x loo (Frankel and Pfeiffer).

eye as whitish points with smooth contents and regular
though sometimes indented borders. Under the micro-
scope they appear as granular, yellowish-brown colonies
with irregular borders (Fig. 79).

When planted in bouillon the organism causes a diffuse
cloudiness at first, but, not being motile, soon settles to
the bottom in the form of a rather flocculent precipitate:
which has a tendency to cling to the sides of the glass.
Sometimes a delicate irregular mycoderma forms upon:

19