THE BRAIN. 
465. 
correspondence may be traced between the dispositions of the 
convolutions in both.’’ This is erroneous: compare together 
the hemispheres of these brains, and tell me whether you can 
find in either of them this “most exact correspondence.” I am 
bound to confess, that after having been, in former years, acrani- 
ologist, my faith began to be shaken, and was at length over¬ 
turned, by rarely finding even ‘Hhe general resemblance” that 
exists in the human brain, and certainly “ no correspondence 
between the convolutions and the superficial structure of the 
skull,” and no possibility of discovering it in the living animal, 
if such correspondence had existed. 
The Divisio?i of the Brain. —The contents of the cranial ca¬ 
vity are divided in pretty nearly the same manner in all quad¬ 
rupeds. There is the cerebrum and the cerebellum j the former 
divided into two lobes, and the latter into three, or rather into 
two, united by a belt. There is considerable difference, however, 
in the relative size of the cerebrum and cerebellum. In the 
human being the cerebellum is about one-ninth of the bulk of 
the brain ; in the ox it bears the same proportion ; in the dog it 
is one-eighth; in the horse one-seventh ; and in the sheep one- 
fifth : this, however, depends upon the age, for it is only in the 
adult animal that the cerebellum is fully developed. We have 
not yet inquired into the functions of these two portions of the 
brain ; and when we do, I fear that we shall not be able satisfac¬ 
torily to account for this difference of bulk. 
The relative situation of the cerebrum and cerebellum present, 
as I stated in my last lecture, only an apparent difference. In 
the quadruped the cerebellum is posterior and even superior to 
the cerebrum ; in the human being it is inferior; but this de¬ 
pends upon the manner in which the head is connected with the 
atlaSi In both the cerebellum is the portion nearest to the fora¬ 
men magnum, and under which the crura cerebri must pass to 
arrive at the medulla oblongata and spinal chord. 
The Difference in the Composition of the Brain. —If I cut into 
the brain, I find it composed of two substances very unlike in 
their appearance. The one from its situation on the outside of 
the brain is called the cortical, and from its reddish asAew colour, 
the cineritious substance ; the other, from its pulpy nature, and 
found deeper in the brain, is termed the medullary substance. 
Long hardening in alcohol has proved them both to be of a 
fibrous structure, and has confirmed the old opinion, that they 
are essentially distinct from each other, as well as of very different 
composition. Placed in apposition with each other, and seem¬ 
ingly mingling, they never change by degrees into one another, 
or run, as it were, into the same mass 
