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foetus, at the different stages of pregnancy, since the time of conception 

 is never very certain, and further, the progress of growth varying much, 

 one foetus at six months shall be as large as another at the full term. Ne- 

 vertheless, at the time of birth, the body is commonly eighteen inches 

 long, and weighs from seven to eight pounds. 



The secretion of bile, like that of the fat, seems to begin, towards the 

 middle of gestation, and tinges the meconium yellow, a mucus previously 

 colourless, which fills the digestive tube; a little while after, the hairs 

 grow, the nails are formed about the sixth or seventh month ; a very thin 

 membrane, which closed the pupil, tears, by what mechanism is unknown, 

 and the pupil is seen. The kidneys, at first manifold, that is to say, 

 formed each of from 17 to 18 separate glandular lobules, unite, and form, 

 on each side, a single viscus. Lastly, the testicles, placed at first, at the 

 side of the lumbar column, and aorta, near the origin of the spermatic 

 arteries and veins, then carried along the iliac vessels to the inguinal rings, 

 directed by the cellular cord, (which Hunter calls the gubernaculum testis,) 

 clear this opening, carrying along with them the portion of the perito- 

 neum which is to form their tunica vaginalis, and the inferior fibres of 

 the smaller oblique muscle. 



This covering of the testicles, furnished by the peritoneum, not only 

 covers these organs, and is reflected again over them, but also rises, in 

 adults, about half an inch high, along the lower part of the spermatic cord. 

 If it do not reach, it is said, to the inguinal ring, it is because the whole 

 portion which, after birth, extended from this opening to near the testicle, 

 has been decomposed, and is reduced to cellular tissue. Upon reflecting 

 on the causes of the spontaneous decomposition of a portion of this perito- 

 neal prolongation, it occurred to me, that nothing was less proved, or more 

 improbable; in fact, in earliest life, the testicles, which have passed out 

 from the abdomen, by the inguinal rings, are very little removed from this 

 opening. The portion of tunica vaginalis, which is carried on upon the 

 cord of the spermatic vessels, rises up to the rings, and even extends be- 

 yond ; communicating with the peritoneum, as is sometimes seen in con- 

 genital bubonocele. It is only in the progress of life, that the testicles 

 descend into the scrotum, still departing from the opening which gave 

 them passage ; so that, in adults, the prolongation, which at first covered 

 the whole cord, which, just after birth, was not more than a few lines 

 long, is found to cover only its lower part, when it is lengthened some 

 inches, without any necessity of decomposition; a phenomenon, which 

 it is as as difficult to conceive as to explain. This opinion, suggested, 

 for the first time, in the first edition of his works, is now almost univer- 

 sally received. 



CCIX. Of the. circulation in the foetus. The principal difference that 

 is found between the foetus and the new-born child, besides the inactivity 

 of the senses, and the repose of the muscles subject to volition, lies in the 

 manner in which the circulation is carried on. Too feeble to assimilate 

 to its own substance foreign substances, the foetus receives from its mo- 

 ther, aliments ready prepared. The arteries of the uterus receive a large 

 supply of blood : this is not all employed for the nourishment of the or- 

 gan itself, but passes, in great part, from the mother to the child, being 

 poured, by the uterine vessels, into the cell of a spongy substance, ad- 

 hering on one side to the uterus, and on the other to the ovum which 

 contains the foetus. 



This cellulo-vascular body, known under the name of placenta, is, as 



-s r. 



