systems that enter into its structure, is directed 
from the centre to the circumference ; it is a 
true exhalation that expels the produce and 
continual destruction of organs ; such is the 
action of the heart, arteries, and all secretory 
glands. Other actions, on the contrary, are 
directed from the circumference towards the 
centre ; and it is by these means that we con- 
tinually receive, from thealiments introduced 
into the digestive organs, the air that pene- 
trates into the internal structure of the lungs, 
and surrounds the surface of the body, the 
elements of its growth and reparation. These 
two motions in an opposite direction, con- 
tinually balance each other, and alternately 
preponderate according to age, sex, sleep, dr 
waking. During sleep, the motions are di- 
rected from the circumference towards the 
centre (motus in sornno intro vergunt, Hip- 
pocrates) ; and if the organs that connect our 
intercourse with external objects, repose, the 
internal parts act with greater advantage.” 
H ence our author would explain, or rather 
trace, the connection of repose with corpu- 
lence; and of inordinate mental or bodily 
exercise with leanness. Sleep may, indeed, 
be so indulged as to reduce man to a con- 
dition of mere brutal existence, as in a case 
related by the author of the above extract, 
that of a man sleeping five-sixths of the day, 
with a digestion always active and easy, and 
with “moral affections circumscribed in the 
desire of aliment and repose.” 
Dreaming is a state intermediate between 
sleep and waking. It is the continued activity 
of some organs while others are in a state of 
! quietude; hence incongruous associations, 
and ali their consequences. For somnam- 
bulism (sleep-walking), see Incubus , in 
Medicine. Sympathies are, 1st, between 
two organs which perform the same function, 
as between the kidneys ; 2d, those which 
have been attributed 'to the continuity of 
membranes, as the pain in the glans penis 
; from ealculary affections of the bladder ; 3d, 
| from the extension of local irritation, in the 
I manner that the excretory duct of the parotid 
; gland -occasions an irritation, which is pro- 
\ pagated ui its substance, and augments its 
| secretion ; 4th, exerted between parts which 
do not appea. to be connected either by 
! nerves, membranes, or vessels; as when the 
i nostrils are irritated, the diaphragm contracts 
and occasions sneezing; 5th, those which are 
considered as resulting from the agency of 
the vital principle, us when the rectum con- 
tracts by the •timulusof excrement. 
Habit. Of the powerand influence of habit, 
every one is sensible. Its operation in the 
animal economy, in relation both to the pa- 
thology of disease and the practice of me- 
dicine, requires assiduous attention. For ex- 
ample: a premature propulsion of the foetus 
disposes to a return of the same accident, at 
! the same period of pregnancy ; thus, at thys 
> time, e-pecial care is requisite in order to 
j obviate this acquired propensity. 
The termination of life has been referred 
to the power of habit, blunting gradually, and 
| at length destroying, susceptibility ot' im- 
j pression from t e agents by which the vital 
; principle had hitherto been supported. “ Life, 
j dependant on the continual excitement of 
! the living solid, by the fluids that are con- 
1 veyed ta it, ceases, because after being ac- 
customed to the impressions that these liquids 
produce on them, irritable and sensible parts 
PHYSIOLOGY. 
become at length no longer able to perceive 
them; their action, gradually destroyed, 
would, perhaps, revive, if the stimulating 
powers were to acquire additional force.” 
For a general view of the organs subser- 
vient to animal motions, (the next subject in 
the order of our arrangement) consult Com- 
parative Anatomy, Yol. I. page 41 4. 
Of the voice, and speech. 
Voice is produced by that air which is ex- 
pelled from the lungs, being made to vibrate 
in passing through the glottis. 
“ Do the different modifications of which 
the voice is susceptible depend on the large- 
ness or smallness of the glottis, or on the ten- 
sion and relaxation of the ligaments that form 
the sides of the. aperture from the glottis into 
the mouth?” which last is, indeed, the true 
organ of this function ; for when an opening is 
made in the larynx below it, no sound is 
produced by the passage of the air. It ap- 
pears, however, that both the size of this 
opening, and the tense or relaxed condition 
of the parietes of the larynx, contribute to 
modify voice, or, as it has been expressed, 
that the larynx is both a wind and a string in- 
strument; voice being always acute in fe- 
males, and in young persons previously to the 
age of puberty, at which time the diameter 
ot the aperture in males undergoes a re- 
markable enlargement, and the state of tension 
in the ligaments of the glottis is always in 
correspondence with the narrowness of this 
opening. 
Voice has a further dependance upon the 
length of the trachea. “ A singer who wishes 
to run through the whole gamut, by passing 
from the upper to the lower notes, evidently 
shortens the neck and trachea, but, vice 
versa, lengthens them to produce a contrary 
effect. 
“ Fhe strength then of the voice depends 
upon the volume of air that can be expelled 
from the lungs, and on the greater or less 
power of vibration of which the parietes of 
the canal are possessed in its passing out- 
wards. Birds, the body of which is mostly 
aerial, have a voice very strong when com- 
pared to their size; their trachea provided 
with a double larynx, is almost entirely car- 
tilaginous, particularly in certain chattering 
birds, as the jay and some others ; while it is 
nearly membranous in the hedgehog, the 
noise of which is almost imperceptible.” 
Speech is the prerogative solely of the hu- 
man species. It is constituted by modifi- 
cations which the voice is made to pass 
through, from the motions of the tongue, lips, 
&c. “ The ape, in which these parts are 
formed as in man, would speak like him, if 
the air in passing out of the larynx did not 
rush into the hyothyroid sacs, in some animals 
iqembranous, but cartilaginous in others, and 
even osseous in the alouette or purr, whose 
howl is so hoarse and frightful. Every time 
the animal wishes to cry, these sacs become 
distended, then emptied, so that it cannot 
furnish the different parts of the mouth with 
sounds to be articulated.” 
Articulated sounds are constituted by 
vowels, the consonants are merely for the 
purpose of connecting vowels together. The 
utterance of consonants is necessarily more 
forced and unnatural than that of vowels ; 
hence the superior harmony of those Ian-, 
4 29 
guages which have the greatest number of 
such letters, as jn the ancient language of the 
Greeks, “ quibus dedit ore rotundo nntsa 
lcqui.” Iior. Hence, on the other hand, the 
harshness of the German, Dutch, and other 
languages. “ It would be difficult,” says M 
Richerand, “ to accumulate a greater num- 
ber or consonants in. one word,” (and, con- 
sequently, to select a word of more difficult 
pronunciation), “ than is found in the proper 
name of a German, called Schmidtgen. ’ 
Singing, stammering, lisping, dumbness, 
and ventriloquism. Singing is performed by 
an enlargement or contraction of the glottis'; 
by an elevation or depression of the larynx ; 
by an elongation or shortening of the neck; 
by an accelerated, prolonged, or retarded in- 
spiration ; and by either long or short, and 
abrupt expirations. “ The agreeableness 
then, or the justness of the voice, the extent 
and variety of inflexions- of which it is ca- 
pable, depend on the correct conformation of 
its organs, on the flexibility of the glottis, 
elasticity of its cartilages, and part icular dis- 
position of different parts of the mouth, nasal 
passages, &c. If the two halves of the larynx 
or nasal fossce are unequally disposed, it is 
sufficient to occasion a defect in precision 
and neatness of the voice.” 
Stammering and lisping are occasioned by 
a tongue too large, its train um being too long';, 
and by deficiency or bad arrangement in the 
teeth. When the apex of the tongue is pre- 
vented from striking properly the tore part of 
the roof of the mouth, an inability is pro-- 
duced of pronouncing the letter r. 
Natural dumbness is almost invariably con- 
sequent upon deafness, and does not arise 
from an inability to articulate, but from an 
entire ignorance of sounds. See Dumbness^ 
and Deafness. 
For the na lire of those sounds produced 
by the ventriloquist, see likewise the article 
Ventriloquism. 
Of generation. 
We now proceed to notice those functions ■ 
which nature has provided for the preservation > 
pot of the individual but ot the species. 
Differences of the sexes. During infancy 
we find the general characters of sex com- 
paratively so indistinct, that some writers 
have been disposed to refer the successive 
developement of the male and female pecu- 
liarities solely to the genital organs. “Propter 
solum uteruin mulier est id, quod cst.” Van 
Helmont. It has, however, been well observ-*- 
ed, that we find from birth an independant 
variety of conformation in the male and the 
female; the former having less mobility of 
constitution, and less delicacy and roundness 
of form than the latter. The muscles of man 
are larger and firmer, the asperities of the 
bones are observable in a greater degree, the 
clavicle is more curved, the shoulders broad- 
er, the pelvis smaller, and the thigh-bones 
have a more outward direction, it is well- 
known to the anatomist, tnat by examining 
attentively the skeleton, even previously to 
the age of puberty, the sex may generally be 
traced. 
Even venereal desires have been imagined, 
by some physiologists to be evolved in- 
dependantly of the evolution of the genital i 
organs. M. Richerand, from Galliot, adduces 
the instance of a female, who, “ when ad- 
