REVIEW. 77 
to institute a series of experiments on the conducting power of 
horn of caloric ; and the results have proved as follow : — 
1. That the conducting power of the crust is inferior to that 
of the sole ; whence we derive the indication in practice, that it 
is absolutely essential that the heated shoe should not be al- 
lowed to come in contact with any substance but the crust. 
2. That caloric is transmitted tardily either through crust or 
sole. 
3. That it is not before the elapse of three, four, or five 
minutes after combustion that the thermometer indicates the 
highest degree of heat in the hoof. 
4. That the thinner the horn of the crust is, the more heat 
becomes transmitted through it to the parts it envelopes. 
Having thus assured myself of the conducting power of heat 
of the hoof, I now sought to ascertain the amount of heat it was 
capable of transmitting to the living tissues enclosed by it, as 
well as the degree of heat required to produce burning . 
Before, however, I proceed to give an account of these ex- 
periments, I wish to shew the anatomical structure of the parts 
situated underneath the sole and the crust, and particularly of 
those subjacent to the points of junction between these two parts 
of the hoof. 
When, through maceration, the horny sole has become de- 
tached from the parts beneath it, we come upon the sub-ungular 
tissue which Lafosse and Bourgelat have named the fleshy 
sole ; and which our honourable president, M. Girard, has de- 
signated, after Malpighi, reticular tissue, upon whose surface we 
observe numerous slender prolongations, filiform, which have 
gone under the names of fibres, filaments, villosities, and in later 
times papillce. Now, these villosities or papillae, which, on ac- 
count of their vasculo-nervous organization, I shall denominate 
villo-papUlce, are extremely numerous over the entire surface of 
the reticular tissue, and particularly around the circumferent 
border of the coffin bone, where they come opposite the parts 
burnt by the hot shoe. These villo-papillse, extremely import- 
ant to be known, and which even up to the present hour authors 
have not described with sufficient minuteness, vary from ^ths 
to / ff ths of an inch in length throughout the entire circumference 
of the fleshy sole. 
Another very remarkable disposition, as it regards hot shoeing, 
and one which has not, that I know of, been pointed out, is that 
every plait of the laminated tissue, before it terminates in the 
circumferent border where it unites with the velvety tissue of 
the sole, sends off numerous papillae in digits or teats, of no 
more than from -^ths tooths of an inch in length. 
Examined through a microscope magnifying 250 times, on 
VOL. XXIV. M 
