532 VARIOLA 



influence of the authority of the latter author as well as of 

 Chauveau, this conception was commonly received in France 

 until recently Warlemont and Hugues discovered that the 

 horse is slightly susceptible to vaccine. Dieckerhoff and 

 Rawitz have made the assertion that the contagious disease 

 observed by certain of the former authors was not pox sickness 

 but sometimes stomatitis, and sometimes dermatitis contagiosa 

 pustulosa, which latter diseases are transmissible to other kinds 

 of animals as well as to cattle. 



Sheep pox as a result of natural infection usually spreads 

 exclusively to sheep, not being transmitted to the closely 

 related goats, and it is not dangerous to man. Human pox is 

 only rarely inoculated into sheep. Efforts to immunize cattle 

 with the contagion of sheep pox against cow pox have not 

 been successful. According to Pound the sheep pox must be 

 considered as a specific disease of sheep. The same conclu- 

 sion has been entertained relative to goat pox. 



The pox of other species of animals, as far as they gen- 

 erally appear, manifest themselves in consequence of an epi- 

 demic in man or an epizootic in one of the species of animals 

 and therefore cannot be considered as independent forms of 

 the disease. 



According to our present knowledge human pox, sheep 

 pox and goat pox present symptoms independent of each other 

 in their beginning and spread, while the pox of the other 

 species of animals always stand in a casual relation to one of 

 the cited forms of disease. But this conception does not agree 

 completely with the relationship of these forms of disease. On 

 the contrary the present agreement in the development of the 

 otherwise specific pathological process makes the opinion 

 probable that the pox disease was a specific entirely independ- 

 ent disease of one of the mentioned species of animals or of 

 man which was also transmissible to other species of animals ; 

 but in the course of time the virus has passed through several 

 generations of different species of animals and has become 

 adapted to the life conditions in the bodies of the different 

 species of animals. As a result of this the virus thus living in 



