BACTERIUM ANTHHACIS. 491 



1.25 //. Frequently very long threads, made up of 

 several rods joined end to end, are seen. 



When obtained directly from the body of an animal 

 it is usually in the form of short rods square at the ends. 

 If highly magnified, the ends are seen to be a trifle 

 thicker than the body of the cell and somewhat indented 

 or concave, peculiarities that help to distinguish it from 

 certain other organisms that are somewhat like it mor- 

 phologically. (See Fig. 82.) 



FIG. 82. 



s 



Bacterium anlhracis, highly magnified to show swellings and concavities at 

 extremities of the single cells. 



When cultivated artificially at the temperature of the 

 body the bacterium of anthrax presents a series of very 

 interesting stages. 



The short rods develop into long threads, which 

 may be seen twisted or plaited together like ropes, 

 each thread being marked by the points of juncture 

 of the short rods composing it. (Fig. 83, a and b.) 

 In this condition it remains until alterations in its sur- 

 roundings, the most conspicuous being diminution of its 

 nutritive supply, favor the production of spores. When 

 this stage begins changes in the protoplasm of the 

 bacteria may be noticed ; they become marked by irregu- 

 lar granular bodies, which eventually coalesce into 

 glistening oval spores, one of which lies in nearly every 

 segment of the long thread, and gives to the thread the 



