THE 
VETERINARIAN. 
VOL. IX, No. 100.] APRIL 1836. [New Series, No. 40. 
ANIMAL PATHOLOGY. 
By Mr. You att. 
LECTURE IV. 
The Nerves of Sensation . 
WE now, for the present, quit the inferior (anterior) surface 
of the spinal cord. You have observed the deep central sulcus 
by which it is divided into two columns — sufficiently distinct in 
all our patients, but in the horse peculiarly prominent : these 
columns, however, connected by minute fibres which shoot 
from side to side and mingle intimately together, occupy the 
whole of the inferior surface of the cord, and from these spring 
the spinal motor nerves. The general bulk of the spinal cord 
varies in different animals. It is twice as large in the horse as in 
the human being, although the brain of the former is not more 
than half the weight of that of the latter; and the difference of 
bulk principally arises from the greater development of the 
motor columns. I need not tell you how beautifully the history 
and destiny of this noble animal illustrate the design and 
effect of such an accumulation of motor power, and of so much 
consentaneous action in the different parts of the frame as the 
habits and destiny of the animal require. While the columns 
are more fully developed in the horse, on account of the expen- 
diture of motor power which is occasionally required ; and there 
are, although denied by some veterinary anatomists, whose 
minute research and general accuracy I hoid in the highest esti- 
mation, these decussating fibriculi, running from one column to 
the other; yet they are much fewer in the quadruped than in 
man, and the sulcus is deepened, as it were, that they should be 
few. There are not so many complicated and delicate combina- 
tions of muscular action required in the simple exertion of speed 
and strength in the one, as in the thousand manipulations which 
are essential to the intellectual improvement and almost to the 
existence of the other ; while the spinal cord of the one is exposed 
to a thousand injuries to which that of the other is rarely subject. 
Ity this difference of bulk and of connexion in the spinal cord 
of the biped and the quadruped, you will readily perceive that 
much light is thrown on the cause, and character, and progress 
VOL. ix. b b 
