562 APPLICATION OF METHODS OF BACTERIOLOGY 



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 raust 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 hacterium 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 dis- 

 tance over the abdomen and thorax, the tissues will be 

 markedly edematous. 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 appearance 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 sections of the organs 

 which have been hardened in alcohol the capillaries are seen 

 to be filled with the bacteria; in some places closely packed 

 in large numbers, at other points fewer in number. Usually 

 they are present in largest numbers in those tissues having 

 the greatest capillary distribution and at those points at 



