'Tborated fluid 1 ! of a nature widely different 
from each other, as well as from that w hence 
they proceed. Thus, what can be more un- 
like than the urine and the blood from which 
.it is prepared; or than the urine itself, and 
every other secretion ? This variety of re- 
sult, like others, has been referred to a me- 
chanical filtration, and to chemical action; 
-but a knowledge of the mechanism of the dif- 
ferent glandular organs, still leaves us igno- 
rant of the actual manner in which is operated 
this extraordinary change ol combination. 
Secretion is, therefore, a vital action ; and 
with this, as an ultimate fact, the physiologist 
roust rest contented, while he is justified in 
instituting a research respecting the chemical 
composition of the fluids formed, and in 
tracing, as accurately as may be, the steps of 
■their formation. 
Secretory processes are divided into three 
kinds: 1st, serous transudation, which is 
effected by a mere termination of arteries on 
the surfaces upon which the fluid is poured 
out, without any intermediate structure ; as 
-on the surface of the body, furnishing the 
•sweat; and on the .membranes of joints, fur- 
nishing the lubricating fluids of these organs. 
2d, Secretion by follicles, crypts, or lacunae, 
which are supplied with a great quantity of 
vessels and nerves terminating on their sur- 
faces, and an excretory duct originating from 
the follicles, &c. in the form of a vas eiferens. 
This kind of gland is found in the ear, in the 
tonsils, and in all parts which secrete mucus. 
The more complicated glands which serve 
for the third kind of secretion, are visceral 
masses, constituted of an assemblage of nerves, 
and all kinds of vessels, disposed in packets, 
and united together by cellular membrane. 
These are called conglum rate glands ; those 
of a more simple and smooth structure are 
named conglobate. 
Secretion of the fat. Every fibre of the 
body is connected, and every organ envelop- 
ed by cellular texture. This membrane, 
•however, does not merely serve the purpose 
of connection .and envelopment, it is likewise 
the secretory organ of the adeps, which is 
found enclosed in separate cells in almost 
every part of the body. During life tins 
substance is in a state of semiflui ity, but 
concretes after death from the cessation of 
vital action, and the immediate reduction of 
animal temperature. The secretion ot fat, 
both as to quantity and, in some measure, as 
>to quality, is differently regulated at different 
periods of life, in different parts of the body, 
and under various circumstances of heath 
In early life the secretion is more abundant 
immediately under the skin; hence the plump 
appearance ol infants. In more advanced 
years the surface of the body is almost desti 
tute of adeps, while the tendency to its de- 
posit is more internal. In an adult man 
in health, the adipose substance is averaged 
at about the twentieth part of the body’s 
weight. 
A chemical analysis of this fluid, proves it 
•to partake more of those principles whic ar 
generally predominant in vegetable fluids, 
than qther animal secretions; that is. it eoi 
•tains but a small pr portion of azote, and an 
.abundance of hydrogen and carbon. Ttu-, cir- 
cumstance, with the phenomena accompany- 
ing its deposit and real) sorption, seem to 
favour the supposition of its being *■ a kind of 
intermedium for a portion ©f the nutritive 
PHYSIOLOGY. 
matter extracted from the food, through 
which it must necessarily pass before it is as- 
similated to the individual, of which it is 
destined to repair the loss.” Thus an in- 
dividual with much fat is able to abstain from 
food much longer than another without this 
supply, and, during such abstinence, the 
collected fat is rapidly reabsorbed. 
Adeps, however, serves other purposes in 
the animal economy. Fat persons suffer less 
from cold than others ; this appears to arise 
from animal oil being a bad conductor of 
caloric. It serves likewise to facilitate mo- 
tion, and by surrounding the extremities of 
the nerves, obviates inordinate sensibility. 
Of nutrition. 
Digestion, by w'hich the aliment received 
into the stomach is deprived of its nutritious 
particles; absorption, which conveys such 
nutritious portions into the fluids ; and the 
circulation, by which it is further conveyed 
to the respective parts in order to undergo 
depuration by the various secretory organs ; 
are all preliminary and subservient to the 
function now to be considered. 
The indivisibility and individuality of the 
living body can only be maintained by an in- 
cessant change of the particles which enter its 
composition. “ Thus the animal machine is 
continually destroyed, and at distant periods 
of life does not contain a single particle of the 
same constituent parts.” The most com- 
monly adduced evidence in favour of which, 
is the effect resulting from feeding animals 
with madder; for during the time that this 
substance is made part of the food, the bones 
become of a red colour, which is again lost 
if the madder is only tor a short time sus- 
pended: proving that there is a constant de- 
composition and reformation even of those 
portions of the frame, which, from their com- 
pact texture, must be supposed the least sus- 
ceptible of change. As then the parts of the 
body are constantly destroyed, new parts of 
the same nature are as constantly required, 
and to supply this demand is the office of 
nutrition. “ A bone, for example, is a se- 
cretory organ that becomes incrusted with 
pho phat offline: the lymphatic vessels, which 
m the work of nutrition perform the office of 
excretory ducts, remove this salt after it has 
remained a certain time in the areola? of its 
texture. It is the same in muscles with re- 
spect to fibrine, and in the brain with albu- 
men.” We, therefore, find animal nutrition 
and organization, to consist in this: that the 
aliments having been converted first into 
chyle, and then into blood, and from this last 
having been furnished the various parts, solid 
.nd fluid, of which the animal is composed, 
such parts are at length separated by the pe- 
culiar action of their respective organs: thus 
the body is supported by intussusception as ii 
nas been denominated ; a process very far dif- 
ferent from that union effected by mechanical 
juxtaposition of particles, or operated by 
chemical affinity. 
Ii has ever been the aim of the physio- 
logist, more especially ot recent times, to de- 
tect the prime, and, in a manner, common 
principle subservient to nutrition, in order to 
estima the proportionate quantity of nutrient 
matter furnished by different- alimentary sub- 
stances. We must. However, assiduously guard 
against that fallacy which would connect itself 
3 H 2 
with our inferences from viewing the process 
of nutritive elimination as a process merely 
of chemistry. The separation and assimi- 
lation of nutritive matter, may be pronounced 
to have greater reference to vital action than 
even to the substances themselves from which 
nutrition is extracted. For example : Let us 
suppose, with Dr. Cullen and many others, 
that the common principle drawn from ali- 
mentary matter is saccharine ; let it even be 
demonstrated that such is the case; it by no 
means thence follows that the administration 
of saccharine matter in any form would be 
the mean of conveying into the system the 
largest portion of nutrition. 
This doctrine it will not be improper 
further to illustrate, by calling the reader’s 
attention to circumstances connected with 
one or two chronic maladies. Diabetes, 
whether originating from a disordered state 
of the assimilative organs, from an improper 
action of the kidneys, or, as appears most 
probable, from the conjunction of these two, 
is occasioned more immediately, or at least 
the emaciation which characterizes it, by a 
deprivation of saccharine matter from the 
frame ; but the remedy for diabetes is not of 
a saccharine nature: on the contrary, if the 
disease admits of cure, such cure appears to 
be best ensured by an abstinence from all ve- 
getable diet, by the exclusive use of animal 
food, and by the administration of certain 
astringent medicines. Again, in the rickets 
of infancy, which has an unquestionable de- 
pendance upon a loss to the bones of their 
due portion of phosphal of lime, the physi- 
cian’s object is not immediately to convey this 
matter into the blood, but to restore that de- 
gree and kind of excitement in the osseous 
vessels, from which the secretion results; and 
this will be effected by materials widely dif- 
ferent, both in composition and abstract 
agency, from the substance, the deficiency of 
which is to be remedied. What quantity of 
phosphat of lime is discoverable by the 
chemist in the common chalybeate prepa- 
tions, or in the nutritive aliment, which, pro- 
perly administered, prove of such obvious and 
extensive utility in the management of the 
complaint in question? Hence, in another 
place, we were induced to remark, that the 
proximate cause of rickets does not so pro- 
perly consist in “ a deficiency of that matter 
which should form the solids of the system,” 
as a deficiency of that excitation upon which 
the formation and deposit of such matter 
are momentarily dependant. See Infancy. 
M. Richerand, in his excellent work on 
physiology, states that “ the marine plant, 
the ashes of which form soda, if sown in a box 
filled with earth that does not contain a par- 
ticle of that alkali, and moistened with dis- 
tilled water, furnishes it in as great quantity 
as if the plant had been growing on the bor- 
ders of the sea, in a swampy soil, always 
inundated by brackish or salt water.” Now 
what would follow a deprivation for a time of 
oxygen, "light, or water, from such plant? 
Certainly a debilitated action, and consequent 
interruption of function. To remedy the dis- 
order thus produced, we should not, how- 
ever, apply to the plant the matter of which 
itself is composed ; but restore those agents, 
through the medium of which it had preserved 
its due vitality. Have not these facts of the 
subserviency of vital support to vital action, 
been too much overlooked in the recommend^- 
