NERVOUS SYSTEM OF VERTEBRATA. 363 
3 80 “much higher, and its importance so much greater, that 
care is taken to guard it from injury.—The term brain 
; commonly applied to the whole mass of nervous matter 
ined within the cavity of the skull ; but this consists of 
ral distinct parts, which have obviously different charac- 
: The principal mass in Man and the higher Vertebrata 
s that which is termed the Cerebrum (fig. 199, a) ; this oceu- 
all the front and upper part of the cavity of the skull, and 
divided into two halves or hemispheres by a membranous 
artition which passes from back to front along the middle 
e. Beneath this, at the back part of the skull, is another 
mass, 6, much smaller, but still of considerable size, termed 
he Cerebellum ; and this also is divided into two hemi- 
enree. At the base or under side of the cerebrum, and 
ompletely covered-in by it, are two pairs of ganglia (1 and g, 
g. 196), which belong to the nerves of smell and sight. We 
hall presently find that these are, relatively speaking, much 
ger in the lower Vertebrata than in the higher. 
450. The several masses of nervous matter contained in the 
are connected with each other and with the spinal cord 
bands of nerve-fibres and tracts of vesicular substance, 
fhich serve to bring the brain into connexion with the nerve- 
funks issuing from the spinal cord. But the Spinal Cord 
las also distinct properties of its own, analogous to those 
hich have been shown to exist in the chain of ganglia in 
msects. The upper part of it, which passes-up into the 
avity of the skull, is termed the Medulla Oblongata (f’, fig. 
97). This is connected with the nerves of respiration, masti- 
tion, and deglutition ; and may be regarded as combining 
tren the respiratory and the stomato-gastric systems of 
ertebrata. The remainder of the spinal cord, which de- 
ds through the vertebral column, sends its nerves to the 
imbs and trunk ; and may be regarded as analogous to the 
‘hain of ganglia by which the corresponding parts are sup- 
ied in Insects. 
451. The nerves which issue from the Spinal Cord, all 
wossess two sets of roots ; one from the anterior portion of 
me cord, the other from its posterior portion (fig. 191). The 
abres which come-off by these two sets of roots, soon unite 
nto the trunk of the nerve, which thus possesses the proper- 
les common to both. It was the great discovery of Sir 
