PHYSIOLOGY. 



ments of Spallan/.ani and others, in which 

 the ova of frog's were readily impregnat- 

 ed by contact of the seminal fluid, but 

 were not at all affected by the vapour or 

 aura. 



The attachment of the fimbri<e of the 

 tube to the ovarium, which experiment 

 has shown to occur during 1 coition, esta- 

 blishes an uninterrupted canal from the 

 uterus to the ovarium, and prevents the 

 semen from becoming diffused in the 

 abdomen. 



The germ of the future being pre- 

 exists in the ovarium, where it is formed 

 by a peculiar action of the part, in short, 

 by a true secretion. This germ, in its 

 original state, is a small vesicle of fluid, 

 first noticed by De Graaf, whence the 

 term of ovula Graafiana, applied to their 

 appearance in the virgin ovary. Here we 

 do not mean to countenance those doc- 

 trines of evolution which suppose, that 

 generation only developes germs that 

 have existed from the beginning of the 

 world. We suppose, that the ova pro- 

 duced by the elaboration of blood, car- 

 ried to the ovaria by the spermatic ves- 

 sels, contain the rudiments of the new 

 beings. But the germs in that state are 

 inert, and require that the seminal spirit 

 should be employed 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 mammalia ; but we infer it 

 here from analogy, and also from the ex- 

 periment of Mr. Hunter, in which the 

 removal of one ovarium from a sow, di- 

 minished in a remarkable degree the 

 number of young produced. 



Festal Existence. This is purely vegeta- 

 tive. The foetus receives the fluids brought 

 by the vessels of the mother to the pla- 

 centa 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 de- 

 gree, independent of that of the mother. 

 To say that it is asleep is erroneous ; for 

 not only are the organs of sense and vo- 

 luntary motion in a state of perfect re- 

 pose, but also several of the assimilating 

 functions are totally unemployed, as di- 

 gestion, respiration, and the generality 

 of the secretions. The foetus, however, 

 performs spontaneous motions, which ac- 

 coucheurs enumerate among the signs of 

 pregnancy. 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 ligature, 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 every observer. 

 Both these organs are developed at the 

 same period of life, and cease together to 

 perform their functions, when the female 

 becomes incapable of contributing to- 

 wards the continuation of the species. 

 The breasts increase in size during preg- 

 nancv, but are never more swelled than 

 after parturition. The infant applies its 

 mouth to the nipple, and sucks ; I. e. 

 forms a vacuum by inspiring, in conse- 

 quence of which the atmospheric pres- 

 sure forces the milk through the lacti- 

 ferous tubes into its mouth. The nipple 

 experiences a vascular turgescence, or 

 kind of erection ; which also affects the 

 excretory 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 un- 

 der the article MAMMAUY GI.AXJI, and the 

 composition of their secretion under. 

 MILK. 



Jlges, Temperametits, &c. Having thus 

 gone through the animal economy, ac- 

 cording to its distribution into particular 

 functions, we shall just contemplate man 

 in a general view, passing through the 

 whole course of his existence, and note 

 the principal epochas of his life, from its 

 commencement to the termination in, 

 death. 



The first perceptible traces of the foetus 

 occur about three months after concep- 

 tion. 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, punctum s aliens. The 

 formation of the bones commences about 

 the seventh or eighth week. The earthy 

 particles are first deposited in nuclei in 

 the clavicles, ribs, vertebrae, larger cylin- 

 drical bones of the extremities, 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 well as of the child, both before and af- 

 ter birth, is more rapid in proportion as 

 it is younger. 



About the middle of pregnancy, the 

 operation of some vital functions is dis- 

 cerned : the secretion of fat and bile com- 

 mences. At a more advanced period of 



