ORGANS OF SPECIAL SENSE 



287 



5.9 mm. head-length, he identifies it positively as a rudimentary 

 organ of Jacobson. 



The septal gland arises on the eighth day from the inner 

 wall of the vestibulum, opposite the base of the vestibular tur- 



- r.2. 



FIG. 165. Transverse section of the olfactory organ of a 

 chick embryo, of 7.5 mm. head length. (After Cohn.) 



f., Line of fusion, e. n., External nasal process, i. n., 

 Internal nasal process. T. 1, T. 2, Intermediate and supe- 

 rior turbinals. 



binal, as a solid cord of cells. This grows backwards in the nasal 

 septum and passes to the outer side and branches, subsequently 

 acquiring a lumen. 



