1018 CHARACTERISTICS OF DIFFERENT AGES. 



face distinct from cranium ; aperture of nose, mouth, eyes, and ears perceptible ; head 

 distinct from thorax : hands and forearms in the middle of the length ; fingers dis- 

 tinct; legs and feet situated near the anus; clavicle and maxillary bone present a 

 point of ossification ; distinct umbilicus for attachment of cord, which at that time 

 consists of the omphalo-mesaraic vessels, of a portion of the urachus, of a part of the 

 intestinal tube, and of filaments which represent the umbilical vessels ; the placenta 

 begins to be formed; the chorion still separated from the amnion ; the umbilical 

 vesicle very large. 



Embryo of two months. Length from 16 to 19 lines ; weight from 150 to 800 grains ; 

 elbows and arms detached from the trunk ; heels and knees also isolated ; rudiments 

 of the nose and of the lips ; palpebral circle beginning to show itself; clitoris or penis 

 apparent; anus marked by a dark spot; rudiments of lungs, spleen, and suprarenal 

 capsules ; caecum placed behind the umbilicus ; digestive canal withdrawn into the 

 abdomen ; urachus visible; osseous points in the frontal bone and in the ribs ; chorion 

 commencing to touch the amnion at the point opposite the insertion of the placenta ; 

 placenta begins to assume its regular form ; umbilical vessels commence twisting. 



Emhryo of three months. Length from 2 to 2 inches ; weight from 1 oz. to H oz. 

 (Troy); head voluminous ; eyelids in contact by their free margin ; membrana pupil- 

 laris visible ; mouth closed ; fingers completely separated ; inferior extremities of 

 greater length than rudimentary tail ; clitoris and penis very long; thymus as well 

 as suprarenal capsules present ; caecum placed below the umbilicus ; cerebrum 5 lines, 

 cerebellum 4 lines, medulla oblongata H 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 umbilical vessels and a little of the gelatin of Wharton; 

 placenta completely isolated ; umbilical vesicle, allantois, and ornphalo-rnesaraic ves- 

 sels have disappeared. 



Foetus of four months. Length 5 to 6 inches; weight 2^ 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; crccum placed near the right 

 kidney; gall-bladder appearing ; meconium in duodenum ; cfecal valve visible ; um- 

 bilicus placed near pubis ; ossicula auditoria ossified ; points of ossification in superior 

 part of sacrum ; membrane forming at point of insertion of placenta on uterus ; com- 

 plete contact of chorion with amnion. 



Foetus of five months Length 6 to 7 inches; weight 5 to 7 oz. ; volume of head 

 still comparatively great; nails very distinct; hair beginning to appear; skin with- 

 out 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 of six months. Length 9 to 10 inches; weight 1 Ib. ; skin presents some 

 appearance 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 dark-red; gall-bladder contains serous 

 fluid destitute of bitterness; testes near kidneys; points of ossification in four 

 divisions of sternum ; middle point at lower end of sternum. 



Fvtus r>f seven 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 disap- 

 pearing; a point of ossification in the astragalus; meconium occupies nearly the 

 whole of large intestine; valvuhe conniventes begin to appear; civcum 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 eight montfis. Length 14 to 16 inches ; weight 4 or 5 Ibs. ; skin covered 

 with well-marked sebaceous envelope; nails reach extremities of fingers; mem- 

 brana 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 

 inguinal ring; middle point nearer the umbilicus than the sternum. 



Foetus of nine months, the full term. Length from 17 to 21 inches; weight from 5 

 to 9 H)s., 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, espe- 

 cially 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 ossification in the centre of cartilage at lower ex- 



