192 INFECTIVE DISEASES. 



Within the last few years a great change of opinion has taken 

 place. Bacteriologists have investigated the whole subject, so that 

 at the present day we know exactly the cause of anthrax. 



Bacillus anthracis (Bacteridie du charbon, Bacillus of splenic 

 fever, Wool-sorters' disease, or malignant pustule). Rods 5 to 20 /A 

 long and 1 to 1 '2 5 /A broad, and .threads ; spore-formation present. 

 As a thorough knowledge of the life-history of this bacillus is of the 

 greatest importance, the various steps to be followed in a practical 

 study of it will be successively treated in detail. Its morphological 



FIG. 92. BACILLUS ANTHRACIS, x 1200. Blood corpuscles and bacilli 

 unstained ; from an inoculated mouse (FRANKEL and PFEIFFER). 



and biological characteristics have been very completely worked out, 

 and it" serves as an excellent subject for gaining an acquaintance 

 with most of the methods employed in studying micro-organisms. 



A mouse inoculated with the bacillus or its spores will die in 

 from twenty-four to forty-eight hours, or more rarely in from 

 forty-eight to about sixty hours. 



Examination after Death. The spleen is found to be considerably 

 enlarged, and may be removed, and examined by making cover-glass 

 preparations, inoculations in nutrient media, and subsequently 

 sections. 



Cover -glass Preparations. In cover-glass preparations of the 

 blood of the spleen the bacilli are found in enormous numbers. 

 Preparations should also be made with blood from the heart and 

 with the exudation from the lungs and other organs ; it will be 



