Eelation of Human and Animal Pox. 301 



man affected with pox, the conclusion is justified that the con- 

 tagion of cow pox represents a modification of the human pox 

 virus which has become attenuated in the human. body. Such 

 virus loses its dangerous properties for man permanently in 

 the body of cattle. 



Jenner shared the belief of the people in the vicinity of Gloucester, 

 that vaccinia invariably results from an infection from horses affected 

 with pox, and that it is therefore identical with horse pox. His view 

 was later shared by Lafosse and subsequently by Bouley, and under 

 the influence of their authority and that of Chauveau, this opinion 

 has been generally accepted in France. In recent times, however, after 

 the findings of Warlemont & Hugues, that the horse is only very 

 slightly susceptible for the vaccinia, Dieckerhoffi and Grawitz asserted 

 that the epizootic disease observed by the French authors did not rep- 

 resent the pox affection, but either a stomatitis or a contagious pustular 

 dermatitis, which diseases may be transmitted to other species of 

 animals, and also to man; and they opposed, in consequence, the pre- 

 vailing view. 



Sheep pox usually spreads only among sheep, and the dis- 

 ease, although very fatal among these animals, does not even 

 pass naturally to the closely-related goats, neither is it danger- 

 ous for man. On the other hand human pox can only excep- 

 tionally be transmitted to sheep (Manson, Simond), and even 

 artificially a severe pox affection can only be transmitted to 

 these animals by intravenous injections of variola virus 

 (Kiichenmeister, Tappe). It is not possible to immunize cattle 

 with pox lymph from sheep against cow pox, and vice versa 

 (Peuch, Voigt), therefore sheep pox must be considered as a 

 specific affection of sheep. 



Croats are likewise only susceptible to the contagion of 

 goat pox, as sheep do not become infected in severely affected 

 goat herds, and it is even difficult to infect them artificially. 

 On the other hand the transmission of sheep pox to goats is 

 also difficult (Bremond, Bonvicini, Noeard), while an infection 

 with human pox is not possible (Voigt) ; finally cattle are not 

 susceptible to goat pox (Bonvicini). Accordingly goat pox may 

 likewise be considered as a specific affection of goats. 



Pox of other species of animals, if such occurs at all, results 

 from an infection from man or from the disease affecting one 

 of the above mentioned species of animals, and therefore can- 

 not be recognized as independent forms of the disease. 



•According to the present state of knowledge, therefore, 

 human pox, sheep pox and goat pox represent independent 

 forms of the disease, occurring and spreading independently of 

 each other, whereas the pox of other species of animals always 

 have some connection with one of the above mentioned forms 

 of the disease. This view however does not at all exclude the 



