TRANSACTIONS OF THE SECTIONS. 123 
Some Remarks on the Motion of the Blood in the Head, and on the 
Uses of the Ventricles and Convolutions of the Brain. By Dr. 
CARSON. 
This paper relates to three points; Ist, the circulation of the blood 
through the head; 2nd, to the evolution and regulation of the heat of 
the head. On the first point little was added to what had been already 
published by the author. The 2nd head also only contains an exten- 
sion of that power of generating and reducing heat, possessed by every 
part of the body to the encephalon. 
This subject, the third point, on which the originality of the commu- 
nication chiefly consisted, explained the contrivances which nature had 
used to retain all parts of the brain itself, and of its connection within 
the head in their natural position, both with respect to the parts of one 
hemisphere of the brain in relation to each other, and to the cranium. 
As it was contended to be fully proved that the substance of the brain 
is liable to decrease and enlargement, like every muscular or soft part 
of the body, in cases of great emaciation or obesity ; and as the brain 
must always occupy the same space, that is, it must always fill the 
cranium ; it was necessary, in these changes of dimensions, to have con- 
trivances for allowing the brain to occupy this space without laceration 
or undue stretching of the substances and appendages of the brain to 
their appropriate parts of the skull. These contrivances consisted of 
two kinds—the ventricles placed in the interior of the brain, and the con- 
volutions on its exterior superficies. The internal ventricles or cham- 
bers were receptacles irregularly formed, all connected with each other 
and with the spinal canal. By these receptacles containing more or 
less of water, according to the extent of actual brain, the existing quan- 
tity of brain was allowed to assume the condition that was fitted to re- 
tain its relations. In this office the ventricles were greatly aided by 
the convolutions of the brain. Had the surface of the brain been 
smooth and continuous, the superficial parts of the brain would in a 
ease, let it be supposed, of great emaciation, be unduly stretched. 
This stretching would be unequal, being required to be greater 
the farther any part of the surface of the brain was distant from the 
middle. In consequence of this, parts of the brain of a person in full 
health, and of the same person in a state of emaciation, would be op- 
posed to different parts of the skull. Protuberances of the brain in 
one case received into depressions of the skull, would, in the other, be 
opposed to protuberances of the skull, and the nerves and blood-ves- 
sels would, in the different cases, have a changed direction, and one 
altogether incompatible with their functions. To prevent these effects, 
nature has nicked the external surface of the brain. The convolutions 
formed by this nicking, in cases of emaciation, have wider interstices 
between them, and become themselves narrower as the furrows are 
mlarged, while the ridges are smaller. These enlargements of the 
furrows cooperate with the ventricles, in cases of greater emaciation, 
in securing to the changed amount of brain its natural position. The 
size of the furrows is formed or filled by an increased vascularity and 
