498 £A CTERIOL OGY. 



sam. This leaves the bacilli stained, while the tissues 

 containing them are decolorized ; or the latter may be 

 stained a contrast-color — with eosin, for example — after 

 dehydration in alcohol and before clearing in xylol. In 

 this case they must be washed again in alcohol before 

 using the xylol. In a preparation treated in this way 

 the rod-shaped organisms are of a purple color, and will 

 be seen in the capillaries of the tissues, while the tissues 

 themselves are of a pale rose color. 



Inoculation into Animals. — Introduce into the 

 subcutaneous tissues of the abdominal wall of a guinea- 

 pig or rabbit a portion of a pure culture of bacillus 

 anthracis. The animal usually succumbs in from thirty- 

 six to forty-eight hours. Little or no reaction at the 

 immediate point of inoculation will be noticed ; but 

 beyond this, extending for a long distance over the 

 abdomen and thorax, the tissues will be markedly 

 cedematous. Here and there, scattered through this 

 (edematous tissue, small ecchymoses will be seen. The 

 underlying muscles are pale in color. Inspection of the 

 internal viscera reveals no very marked macroscopic 

 changes except in the spleen. This is enlarged, dark 

 in color, and soft. The liver may present the appear- 

 ance of cloudy swelling ; the lungs may be red or pale 

 red in color ; the heart is usually filled with blood. No 

 other changes can be seen by the naked eye. 



Prepare cover-slip preparations from the blood and 

 other viscera. They will all be found to contain short 

 rods in large numbers. Nowhere can spore-formation 

 be detected. Upon microscopic examination of sec- 

 tions of the organs which have been hardened in 

 alcohol the capillaries are seen to be filled Math the 

 bacilli ; in some places closely packed in large num- 



