EEELIMINAET EEMAEKS. 175 



This law, to use the language of Erasmus "Wilson, resolves 

 itself into three forms of expression : — 1. That disease affecting 

 a part of a menibrcme is liable to spread to the whole. 2. That 

 disease of the mucous membrane may spread to the sMn, and vice 

 versa. 3. That disease of a part of a membrane may become 

 translated to a distant part of the sMm, and vice versa. 



An intimate knowledge of the above law is of the highest 

 importance in the treatment of those diseases which are pecu- 

 liar to the skin and to the mucous membranes ; especially those 

 of a chronic, specific, and malignant nature ; such as grease, 

 canker, scarlatina, farcy, glanders, and a number of others not 

 necessary to enumerate. 



The colour of the hair of horses seems to hold some myste- 

 rious relation to their breed. There are, comparatively speak- 

 ing, very few thorough-bred horses of a black or iron grey 

 colour ; while greys, blacks, and brovms are the predominating 

 colours of draught horses. 



Grey horses are subject to one disease which I never saw 

 manifested by those of any other colour ; namely, the disease 

 known as melanosis. 



formerly the opinion was current amongst horsemen and 

 veterinary surgeons that white-legged horses are more prone to 

 attacks of grease than dark-legged ones. My experience, how- 

 ever, does not verify this opinion: on the contrary, I have 

 found grease to bear a far more intimate relation to the form of 

 the bones of the extremities than to the colour of the hair. 

 Eound-boned horses are more prone not only to grease, but to 

 other maladies of the skin, than are clean-legged and flat-boned 

 horses. 



"With these preliminary remarks, we vrill now proceed to 

 describe the several diseases of the skin mentioned at the head 

 of this section. 



