466 
MR. YOUATTS VETERINARY LECTURES. 
The fibres of the cineritious portion run in various ways: on 
•the surface of the brain they are vertical,— deep within the 
brain, they take every possible direction. While they are uncon¬ 
nected with the medullary substance, they are in a manner iso¬ 
lated among each other. The medullary fibres are connected 
throughout the brain. They have all a direct or indirect ten¬ 
dency towards the centre and base of the brain: and from their 
common centre, or condensation of substance and influence and 
power, the nerves derive their origin. The nerves seem to be 
prolongations of the medullary substance. The cineritious por¬ 
tion is scattered every where; chiefly distributed towards the 
outside of the brain, but found also deep in its ceatre; and striae, 
or portions of it, at the root of every nerve. The medulla oblon¬ 
gata and the spinal chord are evident prolongations of it. 
The Proportions of Medullary and Cineritious Portio?is in 
different Animals .—The facts that I have just stated lead to the 
most interesting inquiry in which the physiologist can be en¬ 
gaged, viz. a comparison between the brains of various animals— 
the proportions of these two substances in each, and the cha¬ 
racter and destiny of the different animals ; and the conclusion 
drawn from such an inquiry will be arrived at without difficulty, 
and will be perfectly satisfactory. Compare together these 
brains—that of the human being, the horse, and the ox. Ob¬ 
serve, in the first place, the development, greater beyond com¬ 
parison, of the nerves of sense in the brains of the inferior 
animals ; compare the olfactory nerve in the human being and 
the quadruped, (I must maintain that it is a perfect nerve, 
although our best comparative anatomists have degraded it into 
a mere mammillary process); that belonging to the human brain 
is not one-fourth the size of the same nerve in the horse, nor a 
sixth part so large as that in the ox. Compare the optic nerve 
in the biped and the quadruped, the size of the tractus and the 
bulk of the nerve itself—the auditory nerve affords as satisfactory 
a point of comparison. Examine that which I have described 
as the common centre of the medullary substance or influence; 
that which gives origin to every cerebral nerve of sensation and 
of motion ; first, the crura cerebri, mere chords in the human 
being, compared with the broad and bulky pillars of the quad¬ 
ruped. Observe the medulla oblongata, the centre or the con¬ 
densation of the medullary matter of the cerebellum as well as 
the cerebrum—the origin or commencement of the spinal chord 
—connected with loco-motion, with strength and common sensi¬ 
bility—connected too, as we shall hereafter see, with the powers 
of organic as well as animal life. How striking is the difference! 
—the breadth of the medulla oblongata in the human being is 
