DISEASES OF THE HOCK. 



305 



ihe halt3 less tibrupt, and more time lias been given to the 

 cavalry recruit horse £or the evolution of his natural powers, 

 the disease has much abated in prevalence." — (Percivall.) 



The hock described as " tied in below " is that form where 

 the head of the metatarsal and cuneiform bones are small com- 

 pared with the bones above. The cuneiform and metatarsal 

 bones are receivers of weight and distributors of concussion ; 

 their capability to the performance of those functions depends 

 upon their size and development, and upon the breadth of sur- 

 face they present. When not well developed, one cannot fail 

 to see the applicability of the argument that they are predis- 

 posed to spavin, and as a rule practice proves its correctness ; 

 but there are many exceptions, and one often sees a badly- 

 formed hock remaining sound under very severe tests, v^ 



The theory of Goodsir, that the motion of the true hock- 

 joint is like a screw, is well worthy of consideration. I have, 

 by the kindness of Professor, Turner, obtained the loan of a 

 cast of several astragali united together, illustrative of the 

 screw-like direction of its articulating surface. The cast was 

 prepared by Mr. Stirling, the curator of the Edinburgh Univer- 

 sity Anatomical Museum, under Professor Goodsir^s immediate 

 superintendence. Being the result of the observations of ono, 

 to whom, the Edinburgh Veterinary College is so especially:' 

 indebted, it cannot fail to be interesting. 



f lO. 51. — Astragali united to show the screw linesi 



By carefully examining the oblique puUey-like prominences, 

 and the deep groove between them, on the superior articulating' 



