LECTURE ON BACTERIOLOGY. 
363 
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Fig. 2.—Micro-bacteria (Bacteria). A, Bacterium termo; B, same in zoogloea mass (x 600); 
C, same (x 2,100) showing flagella. 
rapidly fatal results when introduced into the circulation of a 
living being. Other examples of this class, resembling in every 
respect, as far as their microscopic features are concerned, the 
septicaemic bacterium, are frequently found in the blood of 
perfectly healthy persons. 
Desmo-bacteria (or bacilli) are rod-like bacteria, occurring of 
various lengths and of different thickness. On this account 
authors have introduced the term vibrio , as applied to the long, 
slender, curved, and thread-like bacillus ; bacilli are not infre¬ 
quently provided with a flagellum, which assists in locomotion. 
The different species of bacilli differ greatly in their microscopic 
appearance ; while some are rounded at their extremities, others 
are square cut, and others pointed. Bacilli may develop by 
division, but their usual mode of development is by spores. You 
will observe in Fig. 3 the bacillus of tuberculosis and anthrax. 
Notice at intervals the dots, which represent the spores from 
which, as the rods break up, future bacilli are developed. 
Spiro-bacteria. In Fig. 4 I present to you drawings of two 
different forms of spiro-bacteria—the spirilla and the spirochetse. 
The former have short, open spirals; the latter long and closely 
wound spirals. The spirillum volutans is often found in drinking- 
water and, in common with some other specimens of this class, 
is provided with flagella, sometimes at both extremities, which 
furnish the means of their rapid locomotion. The spiro-bacteria 
multiply by spores, although little is at present known of their 
