470 Rabies. 



disease during summer time is sufficiently explained by the 

 greater intercourse between the animals, and the same fact ex- 

 plains the frequent appearance of the disease in densely popu- 

 lated districts. In various individuals, however, great differ- 

 ences are noticed, as some animals, even dogs, resist every in- 

 fection. 



The relatively rare occurrence of rabies in Constantinople was formerly ex- 

 plained by the supposition that the breed of dogs there had greater resistance 

 against the contagion, that the disease there generally caused only paralytic symp- 

 toms, and that the rabies , virus was attenuated. Eemlinger found on the contrary 

 that the disease follows its regular course, and that the infectious agent is very 

 virulent. According to his opinion, "the rarity of cases of rabies may be explained 

 by the peculiar way of living and the distribution of the street dogs there. They 

 are not running about the streets, but live in groups in certain streets or parts of 

 streets, strictly watching their places of living, and when a strange dog appears 

 it is at once chased away. When a dog develops rabies, it also remains in the 

 street where it is born and has so far lived, while the healthy dogs by instinct avoid 

 their diseased comrade, and, in ease it should try to escape, it will be surrounded, 

 barked at and compelled to withdraw to its sulking place. Only inexperienced 

 young dogs come near it; therefore, in Constantinople, only young animals have 

 been found with rabies, and human beings have been bitten by these dogs almost 

 exclusively. 



Pathogenesis. If the rabies virus becomes introduced in 

 some part of the body through bites or artificial infection, it 

 penetrates, as suggested already by the theoretical views of 

 Duboue in 1879, as a rule along the nerve tracts of the involved 

 part of the body towards the central nervous system usually 

 without entering the circulation, and from there it is distrib- 

 uted only gradually. The researches of Vestea & Zagari 

 show that after the inoculation of virus into a nerve of the 

 hip of a rabbit the paralysis will first appear in the hind leg, 

 and from there proceed forwards, while after the inoculation 

 into a nerve of the foreleg or under the meninges, a reverse 

 process will be observed. If the nerve connecting an extremity 

 with the spinal cord is severed, the subsequent injection of 

 rabies virus into the respective limb will not produce the dis- 

 ease (Nicolas). If, before the inoculation into a peripheral 

 nerve, the spinal cord is cut through in its entire breadth, only 

 the portion connected with the infected nerves up to the place 

 of division becomes virulent, but not the part on the other 

 side. The results of the inoculation experiments have been con- 

 firmed by the histological researches of Schaffer, who always 

 found intensive changes in the portions of the spinal cord which 

 were connected with the nerves coming from the place of the bite. 

 If the disease occasionally develops after injection into the blood 

 stream or into the peritoneal cavity, the explanation is that sim- 

 ultaneously a nerve was also injured. 



The virus which has reached the central nervous systeia, 

 also moves in centrifugal direction along the nerve tracts. Thus, 

 when the disease has a rapid course, the virus will be contained 

 only in the nerves connected with the place of infection and 

 in the cerebral and spinal tissue, but when the course is slow, 

 the virus after a certain time will disappear from the nerves 



