APPENDIX 



143 



ment. The head occupies different positions. In some it is drawn 

 back as in tetanus ; in others it is drawn down with the nose near 

 the fore legs ; and in still others it is extended as if the animal were 

 sleeping. The period of this complete paralysis varies from a few 

 hours to a few days, but ordinarily it does not exceed 24 hours. 

 Although the animals are unable to move voluntarily, there is usually 

 a reflex action of the limbs until a very short time before death. 



During the period of incubation the temperature of the rabbits 

 remains normal. As the time approaches for the first symptoms to 

 appear there has been in the animals tested an elevation of tem- 

 perature of from I to 2 degrees, which continued for a variable 

 length of time, but rarely longer than 2 days. This is followed 

 by a gradual or usually a more rapid drop to the subnormal, which 

 continues to the end. 



Swine Plague. — Rabbits are most susceptible. Inoculate sub- 

 cutaneously with a bit of the pneumonic tissue, either in a solid 

 piece or in a suspension in bouillon hypodermically. In case of 

 virulent swine-plague bacteria, the rabbit will die in from 16 to 

 36 hours from septicaemia. Pure cultures can be obtained from 

 the blood, spleen, liver, or kidney. Stained cover-glass prepara- 

 tions from these organs show a greater or less number of polar- 

 stained bacteria. 



In case of a more attenuated virus the rabbit will live from a few 

 days to several weeks and possibly months. In these cases there 

 are usually marked local cell infiltrations, with inflammation of one 

 or more of the serous membranes and possibly metastatic abscesses. 



Hog Cholera. — Rabbits are most desirable. They are inoculated 

 in the same manner as with tuberculosis. With ordinarily virulent 

 bacteria the rabbits will die in from seven to ten days. The lesions 

 are essentially a purulent infiltration of the subcutis at the point of 

 inoculation, an enlarged and very dark colored spleen, and areas of 

 coagulation necrosis in the liver. Pure cultures can be obtained 

 from the blood, liver, or spleen. 



Anthrax. — Mice or guinea pigs should be used. They are inocu- 

 lated in the manner described above. They die of septicaemia usu- 

 ally in from 24 to 72 hours. It is not commonly necessary to 

 resort to animal inoculation with this disease. Occasionally, how- 

 ever, it is a very necessary procedure in making an early diagnosis. 



Diphtheria. — Guinea pigs are nearly always used. In certain rare 



