BRA 
nil the organs of sense terminate, and in 
which the soul was formerly supposed prin- 
cipally to reside. See Anatomy. 
The brain and nerves are the instruments 
of sensation, and even of motion ; for an 
animal loses the power of moving a part 
the instant that the nerves which enter it 
are cut. The brain and nerves have a strong 
resemblance to each other ; and it is pro- 
bable that they agree also in their compo- 
sition. But hitherto no attempt has been 
made to analyse the nerves. The brain 
consists of two substances, which differ 
from each other somewhat in colour, but 
which, in other respects, seem to be of the 
same nature. The outermost matter, hav- 
ing some small resemblance in colour to 
wood-ashes, has been called the cineritious 
part; the innermost has been called the 
medullary part. Brain has a soft feel, not 
tmlike that of soap ; its texture appears to 
be very close ; its specific gravity is greater 
than that of water. When brain is kept in 
close vessels so that the external air is ex- 
cluded, it remains for a long time unaltered. 
Fourcroy filled a glass vessel almost com- 
pletely with pieces of brain, and attached 
it to a pneumatic apparatus ; a few bubbles 
of carbonic acid gas appeared at first, but 
it remained above a year without under- 
going any farther change. This is very far 
from being the case with brain exposed to 
the atmosphere. In a few days (at the 
temperature of 60°) it exhales a most de- 
testable odour, becomes acid, assumes a 
green colour, and very soon a great quan- 
tity of ammonia makes it appearance in it. 
Experiments show that, exclusive of the 
small proportion of saline ingredients, brain 
is composed of a peculiar matter, differing 
in many particulars from all other animal 
substances, but having a considerable re- 
semblance in many of its properties to al- 
bumen. Brain has been compared to a 
soap ; but it is plain that the resemblance 
is very faint, as scarcely any oily matter 
could be extricated from brain by Four- 
croy, though he attempted it by all the con- 
trivances which the present state of che- 
mistry suggested ; and the alkaline portion 
of it is a great deal too small to merit any 
attention. 
BRAKE, in naval affairs, the handle 
by which a ship’s pump is usually worked ; 
it operates by means of two iron bolts 
thrust through the inner end of it, one of 
which rolling across two cheeks, in the 
upper end of the pump serves as a fulcrum 
for the brake, supporting it between the 
BRA 
cheeks. The other bolt ‘connects the ex- 
tremity of the brake to the pump spear, 
which draws up the box or piston charged 
with the water in the tube. 
BRAN, the skins or husks of corn, espe- 
cially wheat ground, separated from the 
flour by a sieve or boulter. 
It is of wheat-bran that starch-makers 
make their starch. The dyers reckon 
bran among the non-colouring drugs, and 
use it for making, what they call, the sour 
waters, with which they prepare their seve- 
ral dyes. 
BRANCH, in botany, an arm of a tree, 
or a part, which, sprouting out from the 
trunk, helps to form the head or crown 
thereof. 
Biianch is likewise a term used in genea- 
logy and anatomy. Thus we say, the 
branch of a family, the branch of an artery, 
the branch of a vein. 
BRANCHIAE, gills, in the anatomy of 
fishes, the parts corresponding to the lungs 
of land animals, by which fishes take in and 
throw out again a certain quantity of wa- 
ter, impregnated with air. All fishes, ex- 
cept the cetaceous ones and the petromy- 
zuin, are furnished with these organs of 
respiration ; which are always eight in num- 
ber, four on each side the throat. That 
next the heart is the least, the rest increas- 
ing in order as they stand near the head of 
the fish. 
Each of these gills is composed of a bony 
lamina, in form of a semicircle, for the most 
part ; and on its convex side stand the 
leaves or lamellae, like so many sickles. The 
whole convex part of the lamellae is beset 
with hairs, which are longest near the base, 
and decrease gradually as they approach 
to wards the point. There are also hairs on 
the concave side of the lamellae, but shorter 
than the others, and continued only to its 
middle. 
The convex side of one lamina is fitted 
into the concave side of the next superior 
one ; and all of them are connected toge- 
ther by means of a membrane, which reaches 
from their base half way their height, where 
it grows thicker, and in some measure re- 
sembles a rope. The rest of the lamina is 
free, and terminates in a very fine and 
flexible point. 
As to the use of these gills, they seen! to 
be designed to receive the blood protruded 
from the heart into the aorta, and convey it 
into the extremities of the lamella 1 ; from 
whence being returned by veins, it is distri- 
buted over the body of the fish. 
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