PREVENTIVE MEDICINE 293 



distinct. While Chauveau and others have maintained that small- 

 pox and cow-pox were distinct, Eternod and Haccius* state that 

 human variola may be inoculated to bovines (calves), and after 

 several generations of such passage becomes converted into vaccinia, 

 the virus producing only a localised eruption on reinoculation to 

 man. Gauducheauf has shown in experiments on monkeys that the 

 virus of human variola immunises against that of vaccinia and 

 concludes that they are types or varieties of the same virus. 

 According to PcenaruJ the virus of smallpox cannot be transmitted 

 to pigs. Further controversy has raged as to the connection 

 between equine variola and the disease of horses known as con- 

 tagious pustular stomatitis, but De Jong as the result of his 

 researches concludes that these are one and the same and identical 

 with cow-pox. De Jong was successful in his attempts to trans- 

 mit the disease (contagious pustular stomatitis) from horse to horse 

 and from horse to calf. With virus derived from the horse he 

 was able to produce typical vaccinal pustules in children. He 

 further found that ordinary vaccine was capable of producing 

 stomatitis in horses, and that the virus of stomatitis passes through 

 bacterial filters. 



Sheep-pox (ovine variola) is a scheduled disease in this country 

 to which it is at present exotic, though outbreaks have occurred. 

 It exists in Eastern Europe, parts of Asia and Africa, and occasion- 

 ally in France. The chief vehicle of contagion is the liquid from 

 the vesicles in which the virus is abundantly present. The disease 

 tends to be very virulent when introduced into a new district or 

 country. Certain breeds of sheep possess a high degree of natural 

 immunity, e.g., Breton sheep were found by Nocard|| in 1888 to 

 be practically insusceptible. The virus is fairly resistant to certain 

 destructive agencies, e.g., sealed in tubes and kept in a cool, dark 

 place, its virulence may be maintained for as long as two years. 

 It is not destroyed by a certain degree of cold or desiccation, and 

 it is stated that the disease may hang about infected premises for 

 5 or 6 months and that recovered animals may be infective for 

 as many weeks. Infection is believed to occur by inhalation of 

 virus contained in lymph or in the dust rising from dried scabs. 

 Feeding with lymph fails to infect (Nocardff). The period of 

 *Journ. Com/). Path., 1891, Vol. IV., p. 73, Trans. 



t Trap. Vet. Bull, 1917, Vol. V., p. 132. 

 $Journ. Contp. Path., 1907, Vol. XX., p. 158, Trans. 

 %Journ. Comp. Path., 1917, Vol. XXX., p. 242, Trans. 



|| Journ. Comp. Path., 1889, Vol. II., p. 56, Trans. 

 fl Hutyra and Marek, Spec. Path., Vol. I., p. 305, Trans. 



