THE HUMAN NOSE. 



247 



The double-nostrilled nose has now attained the structure 

 characteristic of Man in common with all other Mammals. 

 Its further development is very easily intelligible : it is 

 limited to the formation of internal and external .processes 

 of the walls of both nasal cavities. Within the cavities 

 develop the " w>se shells," spongy bony structures, over which 

 the olfactory mucous membrane spreads. The first brain 

 nerve, the olfactory nerve, with its delicate branches, passes 



FIGS. 238, 239. Upper part of the body of a human embryo (16 mm. in 

 length) during the sixth week : Fig. 238, from the left side ; Fig. 239, from 

 the front. The origin of the nose in two lateral halves, 

 originally separate, is still plainly visible. The nose and 

 upper lip are disproportionately great in comparison with 

 the rest of the face, especially with the lower lip. 

 (After Kollman.) 



FIG. 240. Face of a human embryo of eight weeks. 

 (After Ecker.) Cf. Frontispiece, Plate I. Fig. Mi 

 Mm, 



