418 BACTERIOLOGY. 



stained in tissues with a strong watery solution of 

 dahlia, after which the tissue is decolorized in 2 per 

 cent, sodium carbonate solution, washed in water, dehy- 

 drated in alcohol, cleared up in xylol, and mounted in 

 balsam. TKis leaves the bacilli stained, while the tissues 

 are decolorized; or the tissues may be stained a contrast- 

 color — with eosin, for example — after the dehydration 

 in alcohol, and before the clearing up in xylol. In this 

 case they must be washed out again in alcohol before 

 using the xylol. In the preparation treated in this 

 way the rod-shaped organisms will be of a purple 

 color, and will be seen in the capillaries of the tissues, 

 while the tissues themselves will be 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. In about forty-eight hours the animal 

 will be found dead. Immediately at the point of in- 

 oculation little or no reaction 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 

 oedematous tissue, small ecchymoses will be seen. The 

 underlying muscles are pale in color. Inspection of 

 the internal viscera reveals no very marked macro- 

 scopic changes except in the spleen. This is enlarged, 

 dark in color, and soft. The liver may present tlie 

 appearance of cloudy swelling ; the lungs may be red 

 or pale red in color; the heart is usually filled with 

 blood. There arc no changes to be seen by the naked 

 eye. 



Prepare cover-slip preparations from the blood and 

 other viscera. They will all be found to contain short 



