90 
BACTERIOLOGY. 
shape is different from other bacteria. Three fairly 
distinct forms are recognized: 
A. The granular type, the granules generally at 
the ends. 
B. The barred type, the granules so arranged that 
the cell looks cross-striped like a barber’s pole. 
C. The solid type, with ends often clbb-shaped. 
They will grow on most of the laboratory media, but 
thrive best on media that contains blood-serum. 
It stains readily with dyes, is not motile, and 
forms no spores. Outside the body direct sunlight 
kills the bacilli in half an hour but in the dust they 
will live for months. On slate-pencils, cups, glasses, 
or toys such as children put in their mouths they will 
live for weeks. In the nose and throat the bacilli 
caused, by the poison made by them, a death or necrosis 
of the mucous membrane. The membrane may extend 
into the nose and larynx causing an obstruction 
to breathing. By far the greater damage is caused 
by the poisons that are absorbed and affect the vari¬ 
ous organs and tissues, particularly the muscle of the 
heart, the kidneys, and the nervous system. The 
effect of the poisons upon the heart results sometimes 
in sudden death, following even slight exertion like 
sitting up in bed. Paralysis may follow diphtheria 
when the nervous system has been attacked. 
Diphtheria in the throat and nose is detected by 
finding the bacilli in the wipings made from the mem- 
niagnosis hrane. It is not safe to rely solely upon the presence 
and appearance of a membrane, because membranes 
