PART I. 



BY C. A. CAEY. 



COW POX. VARIOLA. 



COW POX is a skin disease naturally occurring in cows 

 and rarely appearing in other cattle. It may be trans- 

 mitted by inoculation to calves and to man. The true 

 nature of the virus has never been discovered: various 

 kinds of bacteria have been reported as the cause, and 

 some investigators claim that it is produced by an ani- 

 mal micro-parasite. 



The period of incubation is said to be from two to 

 four days. The eruption occur usually on the teats, the 

 udder and neighboring parts; some observers report 

 eruptions on the inside of the thighs, on the head, and 

 on the scrotum and perineum of the bull. 



The teats at first become slightly swollen, sensitive 

 and somewhat hard ; in a short time appear a number of 

 pimple-like modules, having hard or tumified bases, on 

 the teats and udder around the base of the teats. On 

 transparent skin these modules are scarlet red or rose 

 red ; on white skin they are bluish white, giving a floures- 

 cent reflection; on a dark skin the nodules have a lead- 

 gray color; and, if the skin is thick and tough the pim- 

 ples may be a dirty yellowish gray in color. The pimples 

 or nodules are enlarged popillse of the skin and vary in 

 size, yet they average about one-fourth of an inch in 

 diameter. In about two days the outer layer of the skin 

 is raised, around the center of the enlarged pimple, by 

 viscid, yellowish lymph, which is in separate saccules 

 (multilocular vesicles) ; by thus raising the outer bor- 

 ders of the nodule its center appears depressed. But in 



