738 
PROFESSOR SPOONER’S ORATION. 
in function, and the same in all its susceptibilities in every part 
of the frame. Such, however, is not the case ; for not only, on 
the contrary, will it be found to differ most essentially in all 
these respects in various parts of the same animal, but also in 
the same parts of different animals. So marked, indeed, are its 
peculiarities, that, in a structural point of view, they can scarcely 
be said to bear any analogy to each other, and their susceptibi- 
lities for being acted upon by medicinal agents are altogether 
dissimilar. Regard, for instance, the mucous membrane reflected 
over the inner surface of the mouth: some parts of it are com- 
paratively insensible, while in others dwell the special sense of 
taste, the variability of which in different animals it is unneces- 
sary for me to comment upon. 
Proceeding thence to the pharynx, we find the mucous mem- 
brane still continued ; but it is altogether altered in its structure 
and in its susceptibilities. Trace it onwards in its passage 
down the oesophagus to the stomach, and here again we find, in 
our different patients, marked peculiarities of structure present- 
ing themselves to us, especially so in the horse. In the stomach 
of this animal we see an organ that, when compared with his 
habits, is calculated to surprise and astonish us. We know not 
any animal that employs a greater length of time in the act of feed- 
ing than the horse, if he is left in a state of nature — if he is allowed 
to be out at grass — he is feeding, 1 will not say, with Professor 
Coleman, twenty hours out of the twenty-four, but probably 
more than fifteen. We should consequently be induced to 
say, a 'priori , that he must have a large stomach ; but, instead 
of this, he has a very small one when compared with the same 
organ in other animals, and with the general structure of his 
frame. 
Not only do we observe this peculiarity in the stomach of the 
horse, but we also find that one-half of its inner surface is clothed 
with a continuation of the same membrane that lines the inner 
surface of the oesophagus — a mucous membrane taking on the 
character of cuticular tissue, or that part of the integument which 
possesses but a very low degree of organization and sensibility. 
This is a remarkable structure as connected with the horse — 
one on which the investigations of physiologists have been en- 
gaged for a long period in endeavouring to ascertain the use 
which Nature has ordained that it should perform. Strange 
to say, there is a departure here from that which we usually 
find. In most other parts of the body where we have an alter- 
ation of structure, it takes place gradually ; but the cuticular 
lining membrane of the stomach of the horse terminates abruptly, 
clearly shewing that its function, whatever it may be, is alto- 
