DEVELOPMENT OF THE SENSE ORGANS 



375 



cartilages are developed for its support (Fig. 371). The organ of Jacob- 

 son is not functional in man, but in many animals evidently constitutes a 

 special olfactory organ. 



jr~ Olfactory epithelium 



Ethmo-turbinal I 

 Nasal septum 



JJS Naso-lacrimal duct 

 Maxillo-turbinal 



FIG. 372. Transverse section through the nasal passages of a 65 mm. humar r etus. X 14. 



The Conchae are structures which are poorly developed in man. 

 They appear on the lateral and median walls of the primitive nasal fossae. 

 The inferior concha, or maxillo-turbinal, is developed first in human 



Horizontal ethmoid plate 



Lateral lamella 



Hard pal 



FIG. 373. Right nasal passage of a fetus at term (after Killian). /, Maxillo-turbinal; II-VI, 

 ethmo-turbinals. The slight elevation at the left of / and // is the naso-turbinal. 



embryos (Figs. 371 and 372). It forms a ridge along the caudal two- 

 thirds of the lateral wall and is marked off by a ventral groove which 

 becomes the inferior nasal meatus (Fig. 373). The naso-turbinal is very 



