132 DISEASES OF CATTLE. 



ously. It is not necessary therefore to consider it from an 

 economical point of view, and its description here would be 

 entirely superfluous were it not for the highly important 

 and interesting relation which it bears to small pox in the 

 human being. 



The pox consists of a peculiar eruption on the udder of 

 cows. It rarely appears on bulls or oxen, perhaps only 

 after contagion. The eruption generally takes place on the 

 teats of the udder, but is also, found on other parts of it in 

 exceptional cases. It appears in the following manner: 

 One or more red spots form on the udder, having the ap- 

 pearance of flea-bites. In their centre a red, hard knot 

 appears, which is very small at first. In a few days this 

 knot increases in size, projects more above the surface of 

 the skin, and the latter becomes less red. From the eighth 

 to the tenth day the pox has attained its maximum size, 

 and has then a whitish, yellowish, bluish or silvery appear- 

 ance. ■ The red circle around it has then disappeared, and 

 it has an oval or circular shape of the size of a half dime. 

 It projects above the skin, and is somewhat depressed in the 

 centre. It is tolerably hard, has a cellular, spongy struc- 

 ture like a lemon, and contains a clear, watery, colorless 

 and odorless liquid or lymph, which oozes out in small 

 quantity when an incision is made into the pox. Ten or 

 twelve days after the appearance of the disease, the lymph 

 becomes troubled and changes to pus or matter ; the tumor 

 dries up, and a hard scab is formed, while the size of the 

 eruption diminishes. The scab begins to form in the centre, 

 and gradually spreads to the circumference. It is at first 

 clear and yellow, but soon becomes brown, and finally dark- 

 brown and nearly black. From the twenty-first to the 

 twenty-eighth day, sometimes a little sooner and sometimes 

 a little later, it drops off and leaves a permanent scar, 

 which is reddish at first and afterward recovers the natural 



