SKIN INIARKINGS AND CALLOSITIES OF THE HORSE 



507 



structure identical with hoof horn, and further, that the membrane from 

 which they are developed is a vascular villous membrane, precisely analo- 

 gous to the villous meml>rane of the coronary surface and sole of the 

 horse's foot, which has already been described and figured on pp. 434 and 

 435 of this volume. 



These facts would have consisted remarkably well with the theory of 

 their being remnants of digits, were it not for the cogent objections which 



Fig. 666.— Sections of Chestnut and Ergot of Horse and Bare Patch of Ass 



A, Horizontal section through chestnut of horse — 1, horn; 2, villous secreting membrane; 3, subcutaneous 

 tissue; 4, muscle. B, Perpendicular section through ergot of horse — 1, horn; 2, villous secreting membrane; 

 3, subcutaneous tissue. c, Section through bald patch of ass: a, the bare patch; b, skin— 1, horny layer of 

 epidermis; 2, malpighian (mucous) layer of epidermis ; 3, derma; 4, subcutaneous tissue. 



have been urged against that view. As it is, the identity of structure in 

 the horny growths and the horn of the foot does not tend to assist in the 

 attempt to assign to them any special economy, or in any way to indicate 

 what functions they might have po.ssessed in their more developed 

 condition. 



Plantar pads are represented in fig. 664, A, B (p. 503) in man and 

 dog, and their corresponding positions in the leg and foot of the horse are 

 indicated at c in the same figure. It has been stated already that these 



