PHYSIO tO GY. 
436 
Virility. 
Dccreasei 
Temperaments. 
1 Idiosyncracy. 
Human race. 
Age of decrease. 
J Old age. 
Decrepitude. 
Death. 
Putrefaction, 
Sanguine. 
Muscular, 
Biliary melancholic. 
Lymphatic, 
Nervous. 
European, 
N egro, 
Mongol, 
Iiyperbolean. 
Of digestion , 
Digestion, or that function by which the 
dissolution of the aliment is accomplished, 
and food is thus fitted for the lacteal absorb- 
ents, will be found described under the ar- 
ticle ofDiGESTiox, Yol. I. page 150; and for 
those varieties in the digestive as of all 
ether organs observed in different animals, 
the reader is referred to Comparative 
/lnatoaiy. 
Of absolution. 
Absorption is that process by which the 
/incessant waste of the system from the vai i- 
pus secretions and excretions is constantly 
repaired. Thus after digestion has converted 
the aliment into chyle, this fluid is taken 
up by the lacteals or mesenteric absorbents, 
undergoes a farther preparation in these 
vessels, is thence conveyed to the thoracic 
duct, and at length enters the mass of cir- 
culating blood, to furnish the requisite se- 
cretions, excretions, and exhalations ; in 
this manner a perpetual change is operated 
in the materials of which an animal body is 
composed, “ for it should never be forgotten 
that organized living matter compounds and 
decompounds itself continually.” But this 
composition and decomposition are perpetu- 
ally under the influence of fibrous stimula- 
tion. “ Each orifice of a lacteal and lym- 
phatic, endued with a peculiar degree of sen- 
sibility (susceptibility ?) and power of con- 
traction, dilates or contracts, absorbs or re- 
jects, according to the mode in which it is 
affected by substances that are applied to 
it.” Thus when the chyle is applied to the 
orifices of the lacteal vessels (which have 
been termed chylous absorbents), it is not 
solely by means of capillary or any other 
species of attraction, that this fluid is made 
to enter its appropriate vessels, but such en- 
trance is gained in virtue of the power pos- 
sessed by chyle of stimulating these organs ; 
a demonstration of which principle is fur- 
nished from those substances being rejected 
which have not the power of producing that 
dilatation and contraction just spoken of. 
Another curious fact in support of the 
principle that some substances are not capa- 
ble of exciting the absorbent vessels, is 
furnished by those marks which sailors and 
others are accustomed to imprint on their 
skin, 'i hese are generally formed by first 
pricking holes in the cuticle, and then rub- 
bing the part over with charcoal or gun- 
powder, substances which remain undissolv- 
ed in file fluids, unabsorbed in the lymphatics, 
and therefore continue through ” life. In- 
deed solution is a necessary prelude to every 
case both of lymphatic aid lacteal absorp- 
Yol. II. 
tion. It is then by the peculiar action of 
the lymphatics o'n exhaled fluids, that lymph 
is formed ; and of the lacteals on the chyle, 
that this last becomes animalized. Those 
glandular bodies which are observed in these 
vessels are supposed to have a very import- 
ant influence on their contained fluids ; and 
“although it is not known precisely in what 
these alterations consist of lymph and chyle, it 
may be said that the object of the glands seems 
to be, to occasion the most intimate mixture, 
the most perfect combination of elements ; 
to impress a certain degree of animalization, 
as proved by the greater concrescibility of 
lymph taken from the vasa efferentia, or 
those which pass from glands; to deprive 
them of mere heterogeneous principles, or, 
at least, to alter them that they may not be- 
come hurtful in passing into the mass of hu- 
mours.” Thus we find, that after absorption 
has been in the first'Tnstance effected by vital 
action, the contents of the absorbing vessels, 
still, however, under the same influencing 
principle, are the subjects of a species of 
animal chemistry. 
As the course of the lymph and the chyle 
is less rapid than that of the blood, the 
dilatations, curvatures, and frequent com- 
munications of the lymphatics, must consi- 
derably obstruct the progress of their con- 
tents ; but the principal cause of retardation 
is in the numerous glands just mentioned, 
which every particle of lymph and chyle has 
to pass through previously to its entering 
tlie blood-vessels. 
There are two questions regaining at 
issue respecting the physiology of the ab- 
sorbent system: 1st, Whether the distribu- 
tion of these vessels is universal ; and 2d, 
Whether cutaneous absorption is effected iu- 
dependautly of mechanical violence clone to 
the cuticle. Anatomy has not hitherto de- 
tected absorbents in the substance of the 
brain; but analogy, as well as the circum- 
stances attendant on diseases, disposes us to 
infer almost with certainty, their existence 
in every part. r l he second question, although 
it has recently been negatived by high au- 
thority (Dr. Rousseau, Dr. Currie, M Se- 
guin and others), is generally supposed to bo 
decided in the affirmative. The principal 
facts in support of the latter opinion are, “ the 
increase of weight in the body after a walk 
in damp weather, the abundant secretion of 
the urine after remaining for some time in 
a bath, the evident swellings of the inguinal 
glands after long-continued immersion of 
the teet in water, the effects of mercury ad- 
ministered by friction, the external applica- 
tion of turpentine without friction altering the 
. 3,H 
urine, eveh when, according to some, its en- 
trance into tne system by the lungs had been 
guarded against, &c.” to which Dr. Watson’s 
experiment may be added, of giving a New- 
market jockey, previous to a race, a glass of 
wine, about an ounce in weight, and finding 
immediately after the course, he had gained 
in weight 30 ounces. 
Whether actual nutriment is introduced 
into the system in the way of cutaneous ab- 
sorption, is perhaps extremely problematical. 
Dr. Darwin, however, inclines to this opinion, 
and among the nutrientia in his materia 
medica, classes both substances that are taken 
by the surface and likewise by the lungs. 
Others have supposed, and perhaps with jus- 
tice, that all matter which is nutritive must 
be received through the medium of the lac- 
teals. 
Of the circulation. 
As absorption to digestion , so the descrip- 
tion of the blood’s circulation naturally fol- 
lows to absorption, in tracing the mysterious 
round of animal functions. In describing the 
circulation, we shall, pursuing the order of 
the above table, speak first ot the action of 
the heart ; secondly, of the arteries and 
capillary vessels ; and thirdly, of the veins. 
Of the action of the heart. By referring 
(o the article Anatomy, the reader will find 
the heart described as consisting of four large 
cavities, all of which have a communication 
with each other ; of these the two ventricles 
are in a manner the principal, the auricles 
the accessary cavities. In following the 
blood’s course through these different divi- 
sions, it will be necessary in the first instance 
to suppose, that each cavity is filled and 
emptied in a successive order. We then 
commence the description of the circulation, 
with the blood returning from every part of 
the body, and collected in the two venae cava; 
inferior and superior ; these joining at their 
entrance into the right auricle, pour their 
blood into this auricle, which by consequence 
immediately contracts, and forces the re- 
ceived blood principally into the contiguous 
ventricle : a small part, however, flows back 
into the cava;. The right ventricle now dis- 
tended likewise immediately contracts, and 
the blood is prevented from returning by the 
tricuspid valve, so that only a small part 
flows back, while the principal stream passes 
on into the pulmonary artery, at the en- 
trance of which are the sigmoid valves. The 
blood is now impelled forwards through all 
the very minute divisions of the pulmonary 
artery, and by consequence through the 
lungs ; in these Organs it is exposed to the 
air by the intervention of only a very thin 
