660 APPENDIX. 



Etiology and Pathogenesis. The etiology and patho- 

 genesis of rabies are still but imperfectly understood. 

 The poison, whatever may be its nature, is usually con- 

 tained in the saliva; and as early as the beginning of 

 this century experimental rabies was produced in the 

 dog by inoculation with the saliva of a hydrophobic 

 patient. The bulk of the toxic material appears to be 

 excreted in the saliva of the parotid gland, though a 

 certain small quantity may be excreted by the other 

 salivary glands, and also by the lachrymal glands, the 

 pancreas, and the mammse of rabid animals. The 

 poison may also be found in the suprarenal bodies and 

 in the fluid and substance of the cerebro-spinal nervous 

 system, especially the medulla oblongata; it is found 

 also in the peripheral nerves, though in much smaller 

 quantity than in the central nervous system. It has not 

 been found in the blood, the urine or the aqueous humor 

 of the eye; it has been reported to have been found in 

 the foetus. 



That the disease is due to some form of organism 

 which has the power of multiplying in the tissues and 

 of producing a toxic substance, which appears to act 

 specifically upon the central nervous system, cannot 

 be doubted. As in other specific infectious diseases, 

 the virus is transmitted directly from animal to animal 

 through the medium of some fluid or secretion; it is 

 now very generally recognized that the disease cannot 

 arise anew, as was at one time assumed. In rabies, 

 again, as in other infectious diseases, there is a period of 

 incubation during which the poison appears to increase 

 in quantity. 



The certainty with which the disease may be pro- 

 duced and its severity have been found to be deter- 



