DEVELOPMENT OP THE EMBRYO. 1013 



rudimentary tail; clitoris and penis very long ; thynms as well as suprarenal capsules 

 present; caecum placed below the umbilicus; cerebrum 5 lines, cerebellum 4 lines, me- 

 dulla oblongata 1 J line, and medulla spinalis f of a line, in diameter ; two ventricles of 

 heart distinct. The decidua reflexa and decidua uterina in contact ; funis contains um- 

 bilical vessels and a little of the gelatine of Warthon ; placenta completely isolated ; umbi- 

 lical vesicle, allantois, and omphalo-meseraic vessels have disappeared. 



Foetus of 4 months. Length 5 to 6 inches ; weight 2J to 3 oz. ; skin rosy, tolerably 

 dense ; mouth very large and open ; membrana pupillaris very evident ; nails begin to 

 appear ; genital organs and sex distinct ; caecum placed near the right kidney ; gall-blad- 

 der appearing ; meconium in duodenum ; caecal valve visible ; umbilicus placed near 

 pubis; ossicula auditoria ossified ; points of ossification in superior part of sacrum; mem- 

 brane forming at point of insertion of placenta on uterus ; complete contact of chorion 

 with amnion. 



Foetus o/5 months. Length 6 to 7 inches; weight 5 to 7 oz. ; volume of head still com- 

 paratively great ; nails very distinct ; hair beginning to appear ; skin without sebaceous 

 covering ; white substance in cerebellum ; heart and kidneys very voluminous ; caecum 

 situated at inferior part of right kidney ; gall-bladder distinct ; germs of permanent teeth 

 appear; points of ossification in pubis and calcaneum; meconium has a yellowish-green 

 tint, and occupies commencement of large intestine. 



Foetus 0/6 months. Length 9 to 10 inches; weight 1 Ib. ; skin presents some appear- 

 ance of fibrous structure ; eyelids still agglutinated, and membrana pupillaris remains ; 

 sacculi begin to appear in colon ; funis inserted a little above pubis ; face of a purplish 

 red ; hair white or silvery ; sebaceous covering begins to present itself ; meconium in 

 large intestine ; liver of dark red ; gall-bladder contains serous fluid destitute of bitter- 

 ness ; testes near kidneys ; points of ossification in four divisions of sternum ; middle 

 point at lower end of sternum. 



Foetus of 7 months. Length 13 to 15 inches ; weight 3 to 4 Ibs. ; skin of rosy hue, thick 

 and fibrous ; sebaceous covering begins to appear ; nails do not yet reach extremities 

 of fingers ; eyelids no longer adherent ; membrana pupillaris disappearing ; a point of 

 ossification in the astragalus ; meconium occupies nearly the whole of large intestine ; 

 valvulae conniventes begin to appear ; caecum placed in right iliac fossa ; left lobe of liver 

 almost as large as right ; gall-bladder contains bile ; brain possesses more consistency ; 

 testicles more distant from kidneys ; middle point at a little below end of sternum. 



Foetus of 8 months. Length 14 to 16 inches; weight 4 or 5 Ibs. ; skin covered with 

 well-marked sebaceous envelop ; nails reach extremities of fingers ; membrana pupillaris 

 becomes invisible during this month ; a point of ossification in last vertebra of sacrum ; 

 cartilage of inferior extremity of femur presents no centre of ossification ; brain has some 

 indications of convolutions ; testicles descend into internal ring ; middle point nearer the 

 umbilicus than the sternum. 



Foetus o/9 months, the full term. Length from 17 to 21 inches; weight from 5 to 9 Ibs., 

 the average probably about 6|- Ibs. ; head covered with hair in greater or less quantity, of 

 from 9 to 12 lines in length ; skin covered with sebaceous matter, especially at bends of 

 joints ; membrana pupillaris no longer exists; external auditory meatus still cartilaginous; 

 four portions of occipital bone remain distinct ; os hyoides not yet ossified ; point of ossi- 

 fication in the centre of cartilage at lower extremity of femur ; white and gray substances 

 of brain become distinct ; liver descends to umbilicus ; testes have passed inguinal ring, 

 and are frequently found in the scrotum ; meconium at termination of large intestine ; 

 middle point of body at umbilicus, or a little below it. 



1016. Even at birth, there is a manifest difference in the physical conditions 

 of infants of different sexes ; for, in the average of a large number, there is a de- 

 cided preponderance on the side of the Males both as to the length and the 

 weight of the body. 



a. The length of the body in fifty new-born infants of each sex, as ascertained by Que- 

 telet, 1 was as follows : 



1 " Sur L'Homme," torn. ii. p. 8. 



