50 DISEASES OF THE HORSE’S FOOT 
Having thus paved the way, we are now in a better 
position to discuss our original question (Are the horny 
lamine secreted by the sensitive?), and better able to 
appreciate the work that has been done towards the eluci- 
dation of the problem. 
A most valuable contribution to this study is an article 
published in 1896 by Professor Mettam.* Here the question 
is dealt with in a manner that must effectually 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. Asan 
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 « plane surface, but that it is studded 
by numerous papillary projections, and that these pro- 
jections, with the depressions between them, are covered 
by the cells of the epidermis. 
The corium of the horse’s foot, however, although 
possessed of papille in certain positions (as, for example, 
the papillz of the coronary cushion, and those of the 
sensitive frog and sole), has also most pronounced ridges 
(laminz) which run down the whole depth of the os pedis. 
Each lamina again carries ridges (laminelle) on its lateral 
* The Veterinarian, vol. lxix., p. 1. 
