Variola ; Pox. 34 1 



clearly an outbreak of aphthus fever, which invaded England in 

 that year, and was still an unknown disease to medical men. ^The 

 implication of the heifer which would not have been inoculated 

 with variola through the hands of the milker, and the salivation 

 which is unknown in cow pox, but points directly to the buccal 

 vesicles of foot and mouth disease, are conclusive on this point. 



Ceely later, after many fruitless attempts to convey smallpox 

 to the cow, at last met with results which indicated cowpox, and 

 which he thereafter passsd from cow to cow with the characteris- 

 tic cowpox eruption. 



Fletcher further reports the transmission of smallpox through 

 the horse to the cow, and thence to the child in the form of cow- 

 pox. 



In 1836, Thiele, Kasan, S. Russia inoculated some cows on the 

 udder with smallpox lymph, and conveyed the lymph of the re- 

 sulting vesicles back to man, and from man to man for seventy- 

 five generations of the virus without finding any variation from 

 the type of the true vaccine disease. He repeated the experi- 

 ment with equal success in 1838. 



Such experiments, made before the days of careful antiseptic, 

 or aseptic, laboratory methods, by men who were daily engaged in 

 making vaccinations, cannot be very implicitly relied on, yet the 

 success of Thiele in Central Asia, the early home of variola, may 

 indicate the possibility of a transition, under given eastern con- 

 ditions, which, to say the least, is exceedingly rare in Western 

 Europe or America. 



The experiments of Klein, conducted under modern methods, 

 are more conclusive, and seem to imply the possibility of small- 

 pox passing into cowpox, in the bovine system, under some not 

 yet clearly defined conditions. Until .such conditions are sufiici- 

 ently well known, so that they can be controlled at will, no one 

 can be justified in attempting to produce lymph for vaccination 

 by simply passing smallpox virus through the system of the cow. 



It .seems important to note one or two instances of the evident 

 transmission of smallpox from man to man through the bovine 

 system. 



In i860, Martin inoculated variolous matter, from a man who 

 had just died of smallpox, on a cow's udder, and subsequently 

 inoculated about fifty persons from the eruption caused in the 



