THE MEDULLA OBLONGATA. 
35 
between the human being and the quadruped, as in the medulla 
oblongata. In man it is small and prominent ; in all the domes- 
tic quadrupeds it is wide and bulky, yet comparatively smooth 
and tame. It is widest and most bulky in those quadrupeds in 
which the organic principle prevails, and there is some approach 
to the diminished size, yet the distinct appearance of the diffe- 
rent parts of it, in proportion as the intellectual principle is 
predominant. The different structure of this portion of the spi- 
nal cord in the sheep and the dog will be an instructive study for 
the young pupil. 
Let us look at this portion of the cord — the anterior or inferior 
surface of it. We recognize the two central columns, the cor- 
pora pyramidalia — different in different animals — bold and pro- 
tuberant in the human being; less bold, yet retaining much of 
the same character in the dog and in carnivorous animals ; and 
generally flatter and yet more bulky in the ruminant and the soli- 
pede. They are divided by a sulcus of considerable depth ; but, 
if we examine it closely, we find many fibres decussating , cross- 
ing from the one side to the other, conveying the nervous influ- 
ence which was derived from one side of the brain to the opposite 
side of the cord, and thus accounting for many singular circum- 
stances attending palsy, especially when connected with, or 
arising from, cerebral injury. 
The Corpora Olivaria . — Between theise and the lateral co- 
lumns are, in the human being and the carnivora, two promi- 
nent oval bodies — in the ruminant, two large and flattened ones, 
— the corpora olivaria ; so called from the mixture of yellow and 
cineritious matter which they contain. The division between 
them and the lateral columns is very distinct in the human being 
and the carnivorous quadruped ; in the ruminant it consists of 
little more than a superficial line. You will observe and recol- 
lect this difference of structure — the reason for it will appear 
plainly enough by and by. We examine these bodies a little 
more closely. They are covered by a thin layer of medullary 
matter, but within they are composed almost entirely of cineri- 
tious matter or neurine, very curiously condensed, packed toge- 
ther and folded as if it were for the purpose that as great a 
quantity of it as possible might be contained in the smallest 
compass. 
Whence are these olivary bodies derived ? With what are 
they connected? Of what portion of the brain are they the 
prolongations? When, six or seven years ago, I first ventured 
on this, to a veterinary class, untrodden ground, I was accus- 
tomed to say, that I found the corpora olivaria situated between 
the central and lateral columns in the medulla oblongata, uncon- 
