128 MR. youatt’s veterinary lectures. 
Comparative Size of the Marrow. —The spinal chord varies in 
bulk in our domesticated animals. It is comparatively larger in the 
quadruped than in the biped, and that with evident referenceto 
the different muscular power of each. It is more developed in 
the horse than in the ox or sheep. Notwithstanding the pecu¬ 
liar width of the medulla oblongata in the latter, the spinal 
marrow itself shrinks to a small chord. It is comparatively 
larger in the little horse than in the bulky dray-horse; and evi¬ 
dently more developed in the blood-horse than in him who has 
no pretention to foreign admixture. It seems to have intimate 
connexion with muscular strength and endurance. There is 
much in the bulk of the muscle, and more in its situation or the 
mechanical advantage with which it acts ; but there is more yet 
in the degree of nervous influence which causes the muscle to 
contract. The conformation of the horse is a very important 
and sadly-neglected branch of study. I am sorry to say that 
there are many among us who have no definite or philosophical 
idea of the connexion between the proportion and the position of 
certain parts, and muscular action. Those of us, however, who 
know, or fancy they know’ the most about this, are often egre- 
giously deceived; and the horse, beautifully proportioned, ac¬ 
cording to our notions, has neither spirit, strength, nor endur¬ 
ance. If we could look into the spinal canal, and especially if 
we could comprehend the mechanism of the brain, the mystery 
would be at once unfolded. To the development of the spinal 
chord in carnivorous animals we must chiefly trace their im¬ 
mense strength. Neither the bulk nor the position of the 
muscles of the jaws and neck of the tiger will satisfactorily ac¬ 
count for the ease with which he will bear away, at full speed, an 
animal twice as heavy as himself. Mr. Neilson gives an account 
of a bear steadily carrying a dead horse over a small tree that 
had fallen across a river. The explanation is to be found in the 
excess of stimulus with which the muscles are supplied, and that 
connected with the bulk of the spinal chord, and the corres¬ 
ponding development of the nerves. 
Size of the Spinal Chord in different Parts of the Canal .— 
The varying bulk of the chord in its passage through the spinal 
cavity will afford us some illustration of this. It nowhere fills 
the cavity; for the position of the vertebral column, and the form 
of the canal, are so continually changing, that the marrow 7 would 
be exposed to compression and injury. In the upper part of the 
cervical division of the canal it is of considerable size, for it has 
to supply with nervous influence the numerous and powerful 
muscles that support and rotate the head. As it proceeds 
down the neck it evidently diminishes; but when it approaches 
