BACTERIUM ANTHRACIS 557 



in length. In breadth it is from 1 to 1.25/z. 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, 

 suggestive of the joints of bamboo, peculiarities that help to 

 distinguish it from certain other organisms that are some- 

 what like it morphologically. (See Fig. 95.) 



FIG. 95 



s 



Bacterium anthracis, 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 developmental phases. 



The short rods grow into long threads, which may be 

 seen twisted or plaited together like ropes, each thread being 

 marked by the points of juncture of the segments com- 

 posing it. (Fig. 96, a and b.) In this condition it remains 

 until alterations in its surroundings, the most conspicuous 

 being diminution of its nutritive supply, favor the produc- 

 tion of spores. When this stage begins changes in the proto- 

 plasm may be noticed; the bacteria become marked by 

 irregular granular bodies, which eventually coalesce into 



