CHAP. II.] EVIL AND FARCY — DISTINCTION. 333 



FISTULA in the WITHERS. 



Cause. — Although closely resembling the poll- 

 evil in so many respects as to seem the self-same 

 disorder arising from precisely the same causes, 

 but differing in situation only, we must here pre- 

 mise that some other distinctions are proper to be 

 taken, which it will be necessary to keep in mind. 

 As we have just now seen, poll-evil may be pro- 

 duced without external violence ; but this never 

 happens w\\h fistula in the withers, which is always 

 brought on by external injury — namely, the galling 

 of the saddle : in the first case the tumour frequently 

 turns out a simple abscess, in the present case 

 never, but becomes fistulous at its very earliest 

 stages. This arises from the quantity and great 

 strength of membrane which is found in the shoulder 

 and whole forehand of the horse, in the cellular 

 structure whereof the offensive matter finds an easy 

 receptacle, and spreads its ravages from side to side 

 and inwards. How this operation of nature is per- 

 formed, the reader is instructed in the first book, 

 at sections 26, 21, and at pages 51 to 58 ; the set- 

 ting on of the foreleg to the body, is described as 

 affecting this particular disorder, as well as the 

 tread, pace, and form of going. We have also des- 

 canted at large in the general introductory obser- 

 vations on this whole series of disorders, on the 

 distinctions proper to be kept in mind between 

 one kind of tumour and another, how they are 

 formed, and what description of horses are most 



