The evolution of man : a popular exposition of the principal points of human ontogeny and phylogeny . Figs. 238, 239.—Upper part of the body of a human embryo (16 mm. inlength) during the sixth week : Fig. 238, from the left side ; Fig. 239, fromthe front. The origin of the nose in two lateral halves,originally separate, is still plainly visible. The nose andupper lip are disproportionately great in comparison withthe rest of the face, especially with the lower lip.(After Eollman.) Fig. 240.—Face of a human embryo of eight weeks.(After Ecker.) Cf. Frontispiece, Plate I. Fig. Mi—Mm. 34. 248 THE
The evolution of man : a popular exposition of the principal points of human ontogeny and phylogeny . Figs. 238, 239.—Upper part of the body of a human embryo (16 mm. inlength) during the sixth week : Fig. 238, from the left side ; Fig. 239, fromthe front. The origin of the nose in two lateral halves,originally separate, is still plainly visible. The nose andupper lip are disproportionately great in comparison withthe rest of the face, especially with the lower lip.(After Eollman.) Fig. 240.—Face of a human embryo of eight weeks.(After Ecker.) Cf. Frontispiece, Plate I. Fig. Mi—Mm. 34. 248 THE EVOLUTION OF MAN. from the large brain through the roof of both nasal cavitiesinto the cavities, and extends over the olfactory mucousmembrane. At the same time, by inversion of the nasalmucous membrane, the minor cavities of the nose, which areafterwards filled with air, and which communicate directlywith the two nasal cavities, arise (frontal cavities, cavities ofthe sphenoid bone, jaw cavities, etc.). In this special stageof development they occur only in The external nose is not developed until long after allthese essential internal parts of the olfactory organ havebeen formed. The first trace in the human embryo appearsat the end of the second month (Figs. 238-240). Anyhuman embryo during the first month shows that originallythere is no trace of the external nose. It afterwards growsout from the anterior nasal portion of the primitive form of nose which is characteristic of Man does notappear till a period far later. Much stress is usuallylaid on the
Size: 1298px × 1926px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., book, bookcentury1800, bookdecade1870, booksubjectembryologyhuman
