580 MR. youatt’s veterinary lectures. 
white substance surrounded by layers, or folds of greyish matter. 
All agree that they are very singular bodies; that they here 
come first into sight, unconnected with, and not to be traced into 
any thing above, although they may be traced below into the 
lateral columns, or rather subside, and are lost in them. Be¬ 
hind the corpus olivare is a convex strip or column of medul¬ 
lary matter, which forms the lateral column, and that can be 
traced the w'hole of the way down the spine, between the in¬ 
ferior and posterior roots of the spinal nerves, and from which also, 
in the medulla oblongata, are given out certain nerves devoted to 
organic life—the spinal portion of the organic nerves. 
The Corpora Olivaria in Quadrupeds .—In the ruminantia and 
thesolipeda there is only a faint trace of the corpus olivare to be 
seen. There is no sulcus dividing it from the lateral column. 
There is a very slight rounding of the lateral column—in fact, 
the corpus olivare and the corpus restiforrae together, and not to 
be separated from each other, form the head of the lateral column; 
and when w e cut into the supposed situation of the olivare, we 
find none of the strim or arborescent ramifications of grey mat¬ 
ter which occur in the human subject. We have simply the two 
columns, the lateral being abundantly larger than the central. 
From this portion of the medulla oblongata, there springs another 
root of the portio dura, and also the glosso-pharyngeus, and the 
pneumo-gastric—all spinal organic nerves. I shall have much 
to say of them in another lecture. 
The Spinal Chord .—The medulla oblongata now rapidly nar¬ 
rows and terminates gradually in the spinal chord. Some have 
spoken of a particular change of structure indicating where the 
one ends and the other begins. I have never been able to satisfy 
myself with regard to this; I should say that the medulla ob¬ 
longata is the beginning of the spinal marrow, and that when it 
passes the foramen magnum, its changes its name. For the con¬ 
sideration of the spinal chord, how^ever, we are not yet prepared ; 
w^e must a little retrace our steps, and inquire into the structure 
and functions of the cerebral nerves. 
The Cerebral Nerves. 
The cerebral or animal nerves are soft white chords proceeding 
from the medullary portion.of the brain to various parts of the 
head and body, and by means of wdiich impressions from exter¬ 
nal objects are conveyed to the brain, and sensations are produced 
there, or the volitions of the mind are conveyed to certain organs, 
and voluntary motion is effected. I will not enter into the 
question, w’hether they are extensions of the substance of the 
brain, or mere organs of communication betw'een the brain and 
