914 



TEE SENSORY APPARATUSES. 



The leaves of the podophyllous membrane are immense lamellar papillae, which 

 should be included among the principal instruments concerned in the tactile 

 sensibility of the Horse's foot, and which play a really mechanical part, in con- 

 curring — by their dovetailing with the keraphyllous (or horny) laminae — to assure 

 the solidity of the union of the hoof with the living parts. The cells which 



Fig. 495. 



be d 



HORIZONTAL SECTION OF THE JUNCTION OF THE WALL WITH THE SOLE OF THE HOOF. 



a, Wall, with its horn-tubes; 6, 6, horny laniinse projecting from the wall; c, c, horn-tubes formed 

 by the terminal villi of the vascular laminae, the horn surrounding them and occupying the spaces 

 between the horny laminae, constituting the " white line ; " d, horny sole, with its tubes. 



multiply on their surface have usually but little share in the formation of the 

 horn. This will, however, be alluded to hereafter. 



h. Description of the Hoof. 



The hoof of the Horse — considered as a whole — represents a kind of box that 

 envelopes the inferior extremity of the digit, by fitting closely on the keratogenous 



HORIZONTAL SECTION OF THE WALL, AND HORNY AND VASCULAR LAMINA, TO SHOW THE 

 JUNCTION OF THE LATTER AND THE LAMINELLjE. 



a, Inner portion of the wall with the laminae arising from it ; 6, vascular laminae ; c, horny lamina 

 of aver.ige length ; c', c', unusually short lamina;; c", c", laminellae on the sides of the horny 

 laminae ; d, vascular lamina passing between two horny ditto ; d', vascular lamina passing 

 between three horny laminje ; d", lateral laminellae ; e, e, arteries of vascular laminae which 

 have been injected. 



membrane, to which it is united in the most intimate manner by a reciprocal 

 penetration of prolongations into cavities that exist on the surfaces in contact. 



Its general shape is, as was demonstrated by Bracy Clark, that of the moiety 

 of a cylinder cut obliquely across its middle, and resting on the surface of this 

 section. In nearly all feet, however, it is slightly conical. 



