376 ANATOMY AND PHYSIOLOGY OF THE FOOT OF THE HORSE. 
incorrect ; but it is only by each and every individual considering 
and judging for himself, and, after having found his own conclu- 
sions, giving to them publicity, that we can hope to keep pace 
with the rapid progress of science. 
In all veterinary works we find that the wall, or crust, of thg 
horny case of the foot of the horse is divided into two layers or 
tables, that is, into an outer and an inner table : the outer is said to 
be secreted entirely from the coronary substance, whilst the inner 
one is said to owe its presence to a secretion from the sensible 
lamina. Now it is with this last assertion that I must beg to 
differ, with all due deference, from those who have so stated: I shall 
therefore now proceed to enumerate some few facts which, in my 
opinion, go some way to disprove it ; and, after having done so, I 
shall be glad to hear any other opinion upon the same subject. 
Proceeding from the coronary substance obliquely downwards 
and forwards, we find the sensible laminae, which are nothing more 
than a quantity of thin plates of a somewhat vascular kind of tis- 
sue, perfectly smooth on their external surface, and bound securely 
to the parts immediately beneath them, through the medium of 
layers of dense fibrous material, by some said to possess an elastic 
property, but which I could never detect. Between every two of 
those sensible laminae are received thin plates of horn, correspond- 
ing in exact proportions to themselves, which have been called 
the horny or insensible laminae, and which are found to be firmly 
attached to the internal surface of the inner table of the wall. 
If we make an incision down the centre of the anterior part of 
the hoof so as to expose at once the outer and inner tables of the 
wall with the insensible and sensible laminae, we shall find that, 
from the point of junction of all those parts superiorly to their ter- 
minations inferiorly, there is not the slightest increase or decrease 
in the development of any one of them. This being the case (as 
most certainly it is), I would ask, how can it by possibility be con- 
ceived that, in this normal state of things, we have any secretion 
of horn from the sensible laminae 1 If this was the case, we most 
assuredly must have had an accumulation of such secretion as it 
descended in the general growth of the wall from above down- 
wards. If we separate two of these different laminae from their 
basement structures, we can, with the greatest ease, cause the one 
to glide freely over the other ; but it would be a matter of impossi- 
bility to do this with the sensible and insensible sole, or the same 
of the frog, or the coronary substance and the wall. We find that 
covering the sensible sole, the sensible frog, and coronary sub- 
stance, there is a dense fibrous layer of material for the purpose of 
acting as a protective agent to the minute ramifications of the 
arteries, which are for the purpose of secreting horn, and which 
