THE MANGE OF THE HORSE. 59 



that of the female from 0.40 to 0.48 mm.; the former is 0.39 

 mm. wide, the latter 0.35 mm. The eggs measure 0.17 mm. 

 The illustrations (fig. 30, male and fig. 31, female and 

 egg) were made from specimens which infested some hogs in 

 the vicinity of the State Experiment Farm. The legs of these 

 animals were in a terrible condition, showing that mites had 

 been permitted to inhabit them for a long time. The strange 

 and ridiculous thing about this case was the fact that the 

 hogs were condemned to be killed as suffering from hog 

 cholera. 



THE MANGE OF THE HORSE. 



{Sarcoj)tes scahiei var. equi). 



This itch-mite is found upon the horse, ass, and mule, but 

 •can also migrate to man where it w^ill thrive as well. 

 Though very small it can be readily detected moving among 

 the scurf of an infested skin if a strong magnifying lens 

 is used. Like the other true itch-mites it forms small 

 galleries beneath the scurf-skin, in which it hides and 

 multiplies. If the hide of an infested horse is warmed 

 by the sun, or in a w^arm stable, the mite becomes very 

 active, and is found quite readily by those trained 

 in such work. Prof. Law writes that to obtain speci- 

 mens "it may be needful to tie the scab on the human 

 arm till a prickling is felt, when the acarus will be found in 

 the centre of a minute papule caused by its bite." The writer 

 did not think it absolutely necessary to offer his arm for such 

 a purpose, and this accounts for the fact that no illustration 

 has been made of this parasite. Perhaps some reader may 

 be inclined to offer his assistance, and after isolating the 

 mite in the above manner to donate it to the writer so that 

 a picture can be made. 



Like all true burrowing itch-mites they can not exist for 

 a long time if removed from their burrow and exposed to the 

 dry air; in moist places they can exist, however, for many 

 days, even for several weeks. 



Horses, etc. invaded by such parasites show the presence 

 of them by their restlessness, which is caused by their inces- 

 sant itching about the heads, manes, tails and backs. Here 



