AN Ol'TBREAK OF COW-POX. 279 



quite so severe a character aa in some of the other milkers. Possibly 

 this may be accounted for to some extent by the fact that the pock was 

 covered with a simple dressing instead of being subjected to the irritation 

 and injury incidental to working on the farm. 



Revaccination of the Milkers. — There were in all eight milkers, varying 

 in age from seventeen to flfty-five, who had vesicles on their hands 

 from milking the cows. Seven had been vaccinated in infancy, but not 

 since ; one had been revaccinated on entering the navy at fifteen. They 

 were all revaccinated by a public vaccinator after complete recovery 

 from the casual cow-pox (that is to say, from three to four months 

 afterwards), and were all completely protected. On the other hand, 

 ,two of the three milkers who had escaped infection from the casual 

 cow-pox were also vaccinated, with the result in one of typical 

 revaccination, in the other of very considerable local irritation. 



Retro-vaccbmtion of Calves. — The result of retro-vaccinating calves with 

 the humanised lymph was strictly in accordance with the experience of 

 Ceely, who has pointed out that in retro- vaccination from the milker's 

 hands the results are doubtful, and depend greatly on the animals selected. 

 "Those of a light colour and with thin skins were generally preferred, 

 but often without avail, scarcely one-half of the operations succeeding." 

 " Yaccine lymph, in passing from the cow to man, undergoes a change 

 which renders it less acceptable and less energetic on being returned to 

 many individuals of the class producing it ; some refuse it altogether." 

 Two cases out of four succeeded, and an eruption was produced with 

 all the typical characters of vaccinia, but running rather a rapid course, 

 and the protection passing ofE after a few weeks, while the result 

 obtained in calves inoculated with pus or scrapers from ulcers was in 

 accordance with what is well known to occur if pus instead of lymph 

 is taken for carrying on calf to calf vaccination. 



That the cow-pox in Wiltshire was identical vrith the so-called 

 Hendon cow-disease there can bo little x-oom for doubt, for in both 

 cases we find that — 



1. The disease spread through a whole herd of milch cows. 



2. The disease was characterised by the appearance of vesicles, 

 which were broken by the hand of the milker, and irritated into 

 deep ulcerations. 



3. The disease was conveyed from one cow to another by the 

 hand of the milker. 



4. The vesicular eruption was communicable to the hand of 

 the milker. 



5. The disease was not fatal, and in cows which were killed and 

 examined the post-mortem appearances could not be distinguished 

 from accidental complications. 



6. The naked-eye appearances and the duration of the ulcers of 

 the teats were the same. 



