Pathogenesis, Anatomical Changes. 471 



of the infected extremity, and reappear in the nerves of the 

 other side of the body (Roux, Hogyes) undoubtedly after having 

 passed the involved segment of the spinal cord. In the same 

 way, proceeding in centrifugal direction, it reaches the acinous 

 glands where the conditions for propagation are favorable; 

 thus the tissues of the salivary glands first become virulent, 

 and from there the virus invades the secretion of these glands, 

 the saliva. 



In the central nervous system, the virus exerts its patho- 

 genic effect on the walls of the vessels, causing small-celled in- 

 flammatory foci in the nerve tissues, and on the other hand it at- 

 tacks the nerve cells. The irritation of the nerve cells causes nerv- 

 ous excitement, such as disturbances in consciousness, increased 

 reflex irritability, and, after involvement of the medulla ob- 

 longata, high temperature, polyuria, and diabetes. After a time 

 however, the degeneration of the nerve cells leads to consecutive 

 paralysis affecting finally the respiratory muscles which forms 

 the immediate cause of death. The stage of irritation preceding 

 the degeneration may be of a very short duration, and may be so 

 little pronounced, especially in rabbits, that the disease will show 

 symptoms of paralysis apparently from the start. 



The virus of rabies probably exerts its pathogenic action 

 through some poisonous chemical products, the character of 

 which is yet unknown. 



Anrep has produced out of the cerebral substances of rabid animals 

 a very poisonous, alkaloidal principle, 0,0003-0.0004 g. of which, in- 

 jected subcutaneously, caused lowering of the temperature, paralysis 

 of the extremities, salivation, and death from suffocation. UdranSzky 

 has obtained a solution from the medulla oblongata, which, injected 

 under the meninges of rabbits, killed the animals with symptoms of 

 street rabies. Babes observed only the development of marasmus after 

 injecting large quaatities of brain emulsion of rabid animals, which 

 had lost its infectiousness while, according to Galtier, this substance 

 heated to 100 to 105° C. produced serious toxemia in sheep, goats, and 

 dogs (somnolence, weakness, paralysis). According to Aujeszky, the 

 disease in rabbits injected intracranially lasts only a few hours, while 

 in the experience of Remlinger rabbits injected with virus-free brain 

 filtrate, succumb sometimes in a short time with paralytica! symptoms. 

 {From such animals the disease cannot be transmitted.) 



Very rarely does the virus pass from the female to the offspring; 

 leaving a few positive experiments out of consideration (Kolesnikow, 

 Perroncito & Carita, Loir, Dammann & Hasenkamp) ■. the medulla 

 oblongata of the offspring did not appear virulent (Pasteur, Celli, 

 Zagari, Galtier, Eatz; Konradi found it virulent but the virus therein 

 was weakened). 



Anatflmieal Changes. The post mortem examination of an 

 animal infected with rabies does not show any characteristic 

 changes. Besides the hanging lower jaw, in carnivorous animals 

 and especially in dogs, the stomach is contracted and empty, 



