50 DISEASES OF THE HOESE'S FOOT 



Having thus paved the way, we are now m a better 

 position to discuss our original question (Are the horny 

 laminfe secreted by the sensitive?), and better able to 

 appreciate the work that has been done towards the ehici- 

 dation of the problem. 



A most valuable contribution to this study is an article 

 published in 189(j by Professor Mettam,* Here the question 

 is dealt with in a manner that must efifectually silence all 

 other views save such as are based upon similar methods 

 of investigation — namely, histological examination of 

 sections of equine hoofs in various stages of foetal develop- 

 ment. 



Professor Mettam commences by drawing attention to 

 the error that has been made in this connection by studying 

 the soft structures of the foot separated by ordinary putre- 

 factive changes from the horny covering. ' In this way,' 

 the writer points out, ' a wholly erroneous idea has crept 

 in as to the relation of the one to the other, and the two 

 parts have been treated as two anatomical items, when, 

 indeed, they are portions of one and the same thing. As an 

 illustration, and one very much to the point at issue, the 

 soft structures of the foot are to the horny covering what 

 the corium of the skin and the rete Malpighii are to the 

 superficial portions of the epidermis. Indeed, the point 

 where solution of continuity occurs in macerating is along 

 the line of the soft protoplasmic cells of the rete.' 



In the foregoing description of the skin we have seen 

 that the corium is not a j^laiie surface, but that it is studded 

 by numerous papillary projections, and that these pro- 

 jections, with the depressions l)etween them, are covered 

 by the cells of the epidermis. 



The corium of the horse's foot, however, although 

 possessed of papillae in certain positions (as, for example, 

 the papillffi of the coronary cushion, and those of the 

 sensitive frog and sole), has also most pronounced ridges 

 (laminae) which run down the whole depth of the os pedis. 

 Each lamina again carries ridges (laminellae) on its lateral 



* The Veterinarian, vol. Ixix., p. 1. 



