NATURAL AND CASUAL COW-POX. 315 



advocated the advisability of placing this disease under the Con- 

 tagious Diseases (Animals) Act. 



The numerous pathological details wanting in the early accounts 

 of cow-pox were supplied by the painstaking and laborious re- 

 searches of Robert Oeely. From his classical papers in the Trans- 

 actions of the Px'ovincial Medical Association, we can obtain a 

 complete picture of the natural disease in the cow. 



In Ceely's experience in the Vale of Aylesbury, outbreaks 

 occurred at irregular intervals, most commonly appearing about 

 the beginning or end of the spring, rarely during the height of 

 summer. There were outbreaks at all periods from August to May 

 and the beginning of June, cases being met with in autumn and 

 the middle of winter, after a dry summer. The disease was occa- 

 sionally epizootic, or occurring at times at several farms at no great 

 distance from each other, but was more commonly sporadic or 

 nearly solitary. It was to be seen sometimes at several contiguous 

 farms ; at other times at one or two farms. Many years might 

 elapse before it recurred at a given farm, although all the animals 

 might have been changed in the meantime. Cow-pox had broken 

 out twice in five years in a particular vicinity at two contiguous 

 farms, while at an adjoining dairy, in all respects similar in local 

 and other circumstances, it had not been known to exist for forty 

 years. It was sometimes introduced into a dairy by recently 

 purchased cows. Twice it had been known to be so introduced by 

 milch heifers. It was considered that the disease was pecuhar to 

 the milch cow ; it came primarily while the animal was in milk, 

 and it was casually propagated to others by the hands of the milkers. 

 Sturks, dry heifers, dry cows, and milch cows milked by other hands, 

 grazing in the same pastures, feeding in the same sheds, and at 

 contiguous stalls, remained exempt from the disease. 



For many years, the " spontaneous " origin of cow-pox had 

 not been doubted in the Vale of Aylesbury. In all the cases that 

 Ceely had noticed he could never discover the probability of any 

 other origin. 



Condition of Animal primm-ily affected. — There was much diffi- 

 culty in determining at all times, with precision, whether this 

 disease arose primarily in one or more individuals in the same dairy. 

 Most commonly, however, it appeared to be solitary. The milkers 

 believed they were able to point out the infecting individual. In. 

 two instances, there could be very httle doubt on this point. In 

 August 1838, three cows were affected with the disease. The first 

 was attacked two months after calving and seven weeks after 



