248 HEPWORTH, ON THE STRUCTURE OF THE HORSE’S FOOT, 
two thirds down the wall, into which they dipped, taking the 
same direction, and, no doubt, performing the same functions 
as those from above. Under these circumstances, and, I be- 
lieve, under these only, the vascular laminze do contribute to 
the formation of the wall, and through the medium of the 
wall to that of the horny laminz also; the ends also become 
villous, and, penetrating the sole, fillmg up the spaces between 
the horny laminz which may be traced beyond it. The vil- 
lous appears to be the essential form for the secretion of horn 
in the foot of the horse; that of the sole, frog, &c., are also 
secreted by villi. Ido not think the fact of the wall bemg 
as thick at the top as at the bottom is any proof “that the 
vascular secrete the horny lamine.” As regards sand-crack, 
quittor (separation of the sensible and insensible lamin, by 
abscess or inflammation), there is a secretion thrown out to 
protect the sensible laminze, when exposed ; but I am assured 
by an experienced veterinary surgeon* that it is not horn. He 
says that after operation for sand-crack (removing a portion 
of the wall of the hoof), the sensible laminze become covered 
with soft material, which becomes hard and white. This 
appears only a temporary provision, as the cure is not com- 
plete until the horny covering has been again supplied from 
the coronary substance. It is not improbable that this is 
calcareous matter, as it is formed by the vessels which pene- 
trate the bone, and that it becomes absorbed as the horn 
progresses. I have had no opportunity of examining this 
substance with the microscope; that would decide the ques- 
tion at once. The sensible laminz are very vascular, and the 
question might be asked, Why so, if they have no secretory 
process to carry on? I would answer that, with the constant 
tension they are subject to, not only by the weight of the 
horse, but the concussion in travelling on hard roads, if they 
were not highly organized, they could not perform the func- 
tions allotted to them, but would soon lose their vitality; and 
further, if the horny laminz were tacked on, if I may use the 
expression, they would be torn away. I have examined sec- 
tions of hoofs of the cow, deer, hog, buffalo, and sheep. In 
that of the deer the formation of the laminze commences 
before it reaches the interior surface of the wall; and in the 
hog there are horny bundles iz the wall, which taper off and 
form the laminze; these may be examined either with or 
without polarized light. The coronary frog-band, a por- 
tion of which is represented in fig. 4, is more highly or- 
ganized than I had anticipated. Its villi are distinctly seen 
* Mr. Lawson, Veterinary Surgeon, Manchester, and one of the Exa- 
miners at the London Veterinary College. 
