373 ANATOM V AND PHYSIOLOGY OF THE FOOT OF THE HOUSE. 
for the secretion of the sole ; but, to make up for its deficiency, it is 
receiving the major portion of the blood contained in the lateral la- 
mi nal arteries through some foramen in the os pedis. In no one 
foot injected by me did I ever discover any branches going to those 
laminae sufficient to induce me to believe that they had any thing 
like a secretory office to perform. 
The question might now be asked, whence do the insensible la- 
minae and inner table of the wall arise ? Why, I would an- 
swer, from the coronary substance in common with the outer table ; 
and the difference in the density of the two tables is for the pur- 
pose of allowing of the immediate connexion of a sensible and an 
insensible surface, without fear of concussion resulting therefrom. 
This change in the structure of those parts takes place previous to 
the commencement of the sensible laminae from the coronary sub- 
stance. It is this last-named substance dipping between the 
sensible laminae for a short distance only that causes the insensible 
laminae to be secreted ; and being secreted in this situation, it, 
by virtue of pressure from above, glides down betwixt the sensible 
laminae until it arrives at the place of junction of the sole and the 
crust. Here its office is ended ; but it may be traced to the inferior 
edge of the crust becoming worn off by trituration, in common with 
the inner and outer tables. The dove-tailed connexion which exists 
between the sensible and insensible laminae renders their attach- 
ment very secure, as is shewn by the horse being enabled to sus- 
tain his weight by means of it when both the sole and the frog are 
removed ; but I fear that he could not endure much exertion in this 
state without coming to the ground, as the taking of those parts 
from the foot of the horse, in my opinion, is similar to robbing a tub 
of its hoops. 
I am trying your patience, I dare say; but when I have done, you 
may apply the actual cautery or dissect away just as it may please 
you ; for I cannot leave this subject without first giving to you my 
opinion, from practical experience, on the use of frog setons in cases 
of laminitis. 
During the time that I was engaged as assistant to Mr. Gabriel, 
Secretary to the R.C.V.S., I had an opportunity of witnessing se- 
veral cases of this disorder that occurred in that gentleman’s prac- 
tice. They each of them had the setons inserted in their frogs, and 
every one of them did well, there not being the slightest descent of 
sole to be observed in any one of them. I would therefore recom- 
mend them to every practitioner as the only safe and certain me- 
thod of combatting this fearful disease. 
