PHYSIOLOGY. 
Jiroduced by the elaboratioH of blood, car- 
ried to the Ovaria by the spermatic vessels, 
contain the rudiments of the new beings. 
But tlie germs in that state are inert, and 
require that the seminal spirit should be em- 
ployed to rouse them from their inactivity. 
In birds and reptiles the formation of the 
germ by the female is incontestible ; it is 
not quite so obvious in the class of mamma- 
lia ; but we infer it here from ■analosy, and 
also from the experiment of Mr. Hunter, 
in which the removal of one ovarium from 
a sow, diminished in a remarkable degree 
the number of young produced. 
Fatal Existence. This is purely vegeta- 
tive. The foetus receives the fluids brought 
by the vessels of the mother to the placenta 
for its growth and nourishment. It may be 
considered as a new organ, the produce of 
conception, participating in the general life, 
but possessing a vitality peculiar to itself, 
and, to a certain degree, independent of 
that of the mother. To say that it is asleep is 
erroneous; fof not only are the organs of 
sense and voluntary motion in a state of per- 
fect repose, but also several of the assimi- 
lating functions are totally unemployed, as 
digestion, respiration, and the generality of 
the secretions. The fajtns, however, per- 
forms spontaneous motions, which accou- 
cheurs enumerate among the signs of preg- 
nancy.' It is nourished, like every other 
organ, by appropriating to itself whatever 
is found in the blood, brought by the vessels 
of the uterus proper for its purpose ; and 
the interception of this fluid by the liga- 
ture, or compression of the umbilical chord; 
occasions death. 
Suckling. The close sympathy between 
the uterus and breasts is so obvious, as to 
attract the notice of eveiy observer. Botli 
these organs are developed at the same pe- 
riod of fife, and cease together to perform 
their functions, when the female becomes 
incapable of contributing towards the con- 
tinuation of the species. The breasts in- 
crease in size during pregnancy, but are 
never more swelled than after parturition. 
The infant applies its mouth to the nipple, 
.and sucks ; i. e. forms a vacuum by inspi- 
ring, in consequence of which the atmos- 
pheric pressure forces the milk through the 
lactiferous tubes into ifs mouth. The nip- 
ple experiences a vascular turgescence, or 
kind of erection ; which also affects the ex- 
cretory tubes of the mammary gland, so as 
to cause them sometimes to expel the fluid 
to some distance by jets. The structure of 
the breast is explained under the article 
Mammary Gland, and the composition 
of their secretion under Milk. 
Age», Temperaments, S^c. Having thus 
gone through the animal economy, accord- 
ing to its distribution into particular func- 
tions, we shall just contemplate man in a 
general view, passing through the whole 
course of his existence, and note the prin- 
cipal epochas of his life, from its commence- 
ment to the termination in death. 
The fir,st perceptible traces of the feetus 
occur about three months after conception. 
It is then animated by a very slight kind 
of vegetable life, and possesses true blood, 
and motion of the heart about the fourth 
week. The latter, as observed in the 
chicken, has been named, from the time of 
Aristotle, pundum saliens. The formation 
of the'bones commences about the seventh 
or eighth week. The earthy particles are 
first deposited in nuclei in the clavicles, 
ribs, vertebrse, lai’ger cylindrical bones of 
the extreaiities, lower jaw, and face : a 
very delicate network is’ also seen in some 
of the bones of the cranium. 
As a general observation, it may be af- 
firmed, that the growth of the embryo, as 
Welt as of the child, both before and after 
birth, is more rapid in proportion as it is 
younger. 
About the middle of pregnancy, the ope- 
ration of some vital functions is discerned : 
the secretion of fat and bile commences. 
At a more advanced period of utero-gesta- 
tion, the scalp is covered with a short and 
delicate hair ; the nails are formed ; the 
membrana pupillaris destroyed ; the exter- 
nal ear becomes firmer and more elastic; 
and the testes descend. 
Besides the important changes in the 
whole economy which follow parturition, 
there are certain alterations in the external 
habit of the body. The down which covers 
the face at birth disappears ; the rug® of 
the skin are obliterated ; the anus becomes 
hidden between the buttocks, which are 
now gradually formed. 
The infant gradually brings into action 
the faculties of the mind. It perceives and 
attends to external objects, remembers, de- 
sires, &c. It smiles in the second month, 
and seems to dream at no great length of 
time after birth. The organs of sense be- 
come more complete in their formation. 
The bones of the skull become stronger, 
and the fontanells are diminished. Dentition 
commences about the eighth month. The 
infant may then be weaned, as his teeth en- 
able him to commence the use of more so* 
