S. Respiration, or the exposure of the 
nutritive fluid to the action of the atmos- 
phere. 
4. Circulation, or the distribution of the 
converted matter to every part of the ani- 
mal, for its repair and augmentation. The 
process is named circulation, from the mode 
in which it is carried on in the generality of 
animais. 
5. Secretion, or the separation, and de- 
position of the particles composing the 
structure of animals and vegetables, as well 
as the formation of various substances which 
they produce from the circulating fluids. 
6. Irritability, or the principle by which 
living fibres contract, by means of which 
absorption and circulation are carried on, 
and which is more strikingly manifested by 
the occasional exertions of the muscular 
powers. 
7. Sensation, by which animals become 
conscious of their own existence, and of that 
of external bodies. 
8. Generation, by which new beings, si- 
milar to the parents, are formed and pro- 
duced. 
PARTICULAR ANATOMICAL DESCRIPTION 
OF THE HUMAN BODY. 
After a cursory notice of the cellular stab- 
stance, which forms the grand uniting me- 
dium of the various structures in the body, 
and of membranes, which are formed of 
that substance, we shall proceed to describe 
the other parts, chiefly according to the 
technical arrangement above mentioned. 
Cellulur substance, or cellular membrane, 
tela cellulosa or mucosa of Latin writers, is 
the medium which connects and supports 
all the various parts and structures of the 
body. Any person may gain a general no- 
tion of this substance, by observing it in 
joints of veal, where it is always inflated 
by the butchers. It consists of an assem- 
blage of fibres and laminae of animal matter, 
connected to each other so as to form innu- 
merable cells or small cavities, from which 
its name of cellular is derived. It pervades 
every part of the animal structure. By 
joining together the minute fibrils of muscle, 
tendon, or nerve, it forms obvious and vi- 
sible fibres; it collects these fibres into 
large fasciculi ; and by joining such fasci- 
culi or bundles to each other, constitutes 
an entire muscle, tendon, or nerve. It 
joins together the individual muscles, ahd is 
collected in their intervals. It surrounds 
each vessel and nerve in the body ; often 
connecting these parts together by a firm 
kind of capsule, and in a looser form join* 
ing them to 'the neighbouring muscles, &c. 
When condensed into a firm and compact 
structure, it constitutes the various mem- 
branes of the body, which, by long mace- 
ration in water, may be resolved into a 
loose cellular texture. Its general conden- 
sation on the surface of the body constitutes 
the cutis, or true skin, which is, in fact, a 
membrane. In the bones it forms the basis 
or ground-work of their fabric, a receptacle, 
in the interstices of which the earth of bone 
is deposited. As cellular substance is en- 
tirely soluble in boiling water, it is ascribed 
by chemists to that peculiar modification of 
animal matter termed gelatine. In conse- 
quence of its solution by the united agencies 
of heat and moisture, the muscular fibres 
separate from each other, and form the 
other structures of the body. This effect is 
seen in meat which is subjected to long boil- 
ing or stewing for the table, or indeed in a 
joint which is merely overboiled. 
Its watery solution assumes, when cold, 
the appearance of jelly ; and, after a par- 
ticular mode of preparation, constitutes 
glue. 
The interstices of the cellular substance 
are lubricated and moistened by a serous or 
watery fluid, poured out by the exhalant 
arteries, and again taken in by the lympha- 
tics. It thus acquires a pliancy and soft- 
ness, which adapt it particularly to serve as 
a connecting medium for parts, which have 
motion on each other. The importance of 
this property will be best understood by ob- 
serving the effects of its loss. Inflammation 
or abscess often causes an induration or con- 
solidation of the Cellular texture, by which 
the integuments are fixed to the muscles, 
the muscles are firmly united to each other, 
and to the surrounding parts, and the mo- 
tions of the whole are considerably im- 
paired. 
From the universal extent of this cellu- 
lar texture, two conclusions may be drawn ; 
1st, it forms the basis of the whole animal 
fabric, in stach a way, that if we conceive 
every part removed but this, the form 
of the whole would still be expressed in cel- 
lular substance ; 2ndly, it forms a connec- 
tion and passage between all parts of the 
body, however remote in situation, or dis- 
similar in structure. For the cells of this 
substance every where communicate ; as 
we may collect from facts of the most com- 
mon and familiar occurrence. In emphy- 
sema, where air escapes from the lung 
wounded by a broken rib, into the cellular 
