41 8 
tioa and imagined modus operand! of some me- 
dicines of modern physicians? When Dr. Dar- 
win inferred that calcareous earth contributes 
to the nourishment of animals and vegetables, 
because “whatever has composed a part of 
an animal or vegetable, may again, after its 
chemical solution, become a part of another 
vegetable or animal,” was not this vital agency 
and power ot actually' converting materials 
into those of an opposite nature, in some mea- 
■sure disregarded? But this is not the place 
lor speculation. It is our business rather to 
compress than dilate : and we shall conclude 
by observing, that the principle now con- 
tended for, however^ important, is not to be 
received or acted upon, either in articles of 
food or medicine, in an unqualified or un- 
limited sense. A due supply of appropriate fuel 
as well as of stimulus, is necessary to support 
the flame of life. See M ateria Medica. 
It will be proper before quitting this sub- 
ject, to observe, that as animal matter has 
been proved principally to differ from ve- 
getable, in containing a larger proportion of 
azote than the latter, and the vital process of 
nutrition or animalization, however effected, 
has been judged to be a species of azolili- 
eation, the following extract on this subject is 
given from the work just alluded to of M. 
Richerand: “ Halle believes that the hydro- 
carbonated oxide, or principle of nutrition, 
is combined with oxygen in the stomach and 
intestinal canal ; whether the latter principle 
is introduced with the food into the prim* 
Vis, or furnished by the decomposed humours. 
The intestinal fluids suffer their azote to be 
disengaged, which is carried to the alimentary 
base, and replaces the carbon that had been 
attracted by oxygen to form the carbonic 
acid. This gas, when in the lungs, and again 
subjected to the action of atmospheric oxygen, 
carries off a certain portion of its carbon; and 
as it disengages the azote from venous blood, 
it effects a new combination of this principle 
with the chyle ; and when propelled to the 
skin, the atmospheric oxygen again disen- 
gages its carbon, and completes its azotiti- 
cation. Perhaps even the cutaneous organ 
answers similar purposes to the lymphatic 
system, as the pulmonary organ may effect 
to the sanguiferous system.” 
It will be obvious to the reader, that the 
above theory supposes nutrition to consist in 
the constant loss of carbon, and constant 
supply of azote. It is admitted, however, not 
to account for the formation of phosphoric 
salts, adeps,. and many other substances. It 
!s, therefore, at least defective. 
On sensations. 
The arrangement we have adopted now 
leads us to notice those functions “ which 
connect us with surrounding objects and it 
was our original design in the present article 
to have treated at length on the physiology 
of the senses, especially of sight and hearing. 
Asiliese last subjects, however, could not be 
made interesting or. even intelligible, without 
connecting them with the philosophy of light 
and of sound, it has been judged more ex- 
pedient, in order to avoid repetition, to con- 
fine their consideration exclusively to the 
articles Optics and Sounds. The anatomy 
of the organs will be found under the article 
Anatomy. 
Of smell. As the expansion of the optic 
4|erve into the retina, constitutes the imme- 
mysroLoGY. 
diate instrument of vision, by being peculiarly 
invested with the faculty of perceiving light ; 
as the portio mollis of the auditory nerve, is 
in like manner the direct medium for trans- 
mitting the sepsation of sounds to the sen- 
sorium commune; so the organ of smell, con- 
stituted by a distribution of the olfactory 
nerves on that membrane which lines the 
nasal fossa*, is formed to receive, exclusively, 
the sensation of odours. It is apparently in 
proportion to the depth and extent of these 
fossa;, (affording a larger surface to the 
pituitary membrane,) that the perception of 
smell is variously regulated in different ani- 
mals, and in some measure in different in- 
dividuals of the same species ; and the mem- 
brane itself requires to be in a perpetual state 
of moisture. 
It is supposed by some that the olfactory 
nerves do not extend into the sinuses, but 
that these cavities merely assist the sense bv 
longer retaining a greater mass of air, which 
is loaded with those odoriferous particles that 
constitute the exciting cause of this percep- 
tion. The nasal organs are supplied with 
numerous small branches arising from the 
fifth pair of cerebral nerves ; but these 
branches do not, according to M. Richerand, 
answer any further end, than that of con- 
tributing to general sensibility. The excita- 
bility to odours exists, according to our au- 
thor, exclusively in those which are com- 
monly denominated olfactory nerves. 
Of taste. Every sense has been said to be 
strictly a modification of feeling : that of taste, 
however, approaches nearer than any other 
of the senses, even in its organization, to that 
ot simple or proper feeing; the surface of 
the tongue, which is the principal residence 
of this perceptibility, only varying from the 
common integuments in being thinner, more 
vascular, and having crypt*, or follicles, 
which secrete the mucus of the tongue. These 
are situated in greatest number near its tip, 
and are erected “ when we masticate high- 
flavoured food, or have a strong desire for 
any savoury dish.” “ It is observed that the 
sense of taste in different animals is more 
perfect in proportion as the nerves of the 
tongue are larger, the skin finer and more 
moist, its texture flexible, surface extensive, 
motions more easy and varied. The sense 
ot taste in man would, perhaps, be more de- 
licate than that of any other animal, if he 
was not to blunt its sensibility early in life 
by strong drinks, spicy ragouts, and all the 
refinements of luxury that are daily invented.” 
“Is the lingual branch of the liftli pair of 
nerves alone adapted for the perception of 
taste? Do not the ninth pair equally serve 
for the same purpose ?” This last question 
of M. Richerand has, we believe, generally 
been answered in the negative. It is from 
the fifth pair that the crypt*, just spoken of. 
are supplied. 
On touch. This has been with some pro- 
priety denominated the elementary sense, 
and all others considered as merely modifi- 
cations accommodated to certain properties 
ot bodies. “ Every thing that is not light, 
sound, odour, or savour, is appreciated by 
the touch.” This sense resides throughout 
the whole extent of the nervous system ; the 
peculiar organ, however, of touch, or that by 
which we come to a knowledge of the^ qua- 
lities of objects, is the cutis, spread over the 
external surface- of the body, Tn some parfj. 
this sense is peculiarly modified ; in the skin, 
for example, covering the apices of the fing- 
ers ; and in such parts we meet with something 
resembling the papill* on the tongue ; but, 
perhaps, not exactly similar, as they are ra- 
ther constituted of nervous projections, than 
of glandular crypt* : they are surrounded by 
an extremely fine vascular membrane, \\ hen 
the sense of feeling is exercised, these papill* 
are supposed to swell and elevate the epider- 
mis, which in itself i s totally* insensible to all 
such stimuli as act exclusively on living fibre. 
The epidermis, like the nails and hair, which 
last proceed from it, is a mere defence of the 
body, unorganized, and consequently de- 
stitute of excitability. 
Action of. the nerves. On this subject 
every thing is conjectural. We have not in 
this instance the assistance of anatomy for 
any thing farther than the fact, that the nerves 
are the organs through which the sensitive 
faculty is developed. The form, appearance,, 
and mode of attachment of the nerves, are 
sufficient evidences that they do not act as 
vibratory chords, according to the supposition 
of some theorists ; that they are tubes for 
conveying a fluid from and to the cerebral 
mass, is inconsistent with what has been dis- 
covered respecting the minuteness of divisi- 
bility in their librill* ; it likewise appears 
incompatible with what may be called the 
reacting communications between the centre 
or centres of sensation, and the sensitive 
organs : and we have already had occasion 
to say, that the extensive and very important 
discoveries of modern chemistry, have only 
brought us acquainted with a greater number 
of exciting agents ; they do not appear to 
have cast any light upon the question respect- 
ing the actual mode of nervous or muscular 
excitation. 
With respect to the analysis of our sen- 
sations, the production of ideas, and the com- 
parative estimate of the human understanding 
with that of the instinctive and sensitive- 
faculties of the inferior animals, we cannot 
be expected in this place to institute any in- 
quiry. W r e must be content with expressing 
our opinion, that endeavours to establish an 
identity of faculty in the man and the brute 
(if the dispute is not a mere logomachy), 
have failed of their object ; and as we believe- 
that the fables of the Hamadryades are not 
realized in the “ trees of our forests,” “so we 
still flatter ourselves, notwithstanding the in 
dications of reason, and the great powers of* 
imitation which have been exhibited by some 
individuals of the ape species, that the human 
intellect is of anature essentially different from 
that of the monkey.” 
Of sleep, dreaming, somnambulism, sym- 
pathies, habit. The condition and the ex- 
citing causes of sleep, need no description ; . 
its proximate cause must necessarily lie in the- 
same obscurity with those of other brainular 
and nervous affections. The artificial sleep 
which has been procured by pressure on the 
brain, proves nothing with respect to the 
actual condition of this organ in the sleep of 
nature; it is rather apoplexy than sleep that 
is thus occasioned. With respect to the 
phenomena attendant upon sleep, it has been 
well observed, that “ the human body presents 
with tolerable accuracy the model of the 
centripetal and centrifugal powers of antient 
philosophy. The motion ©f several ©f th$. 
