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MANUAL OF PHYSIOLOGY. 



mentary canal of the cochlea. The angle lying next to the neural 

 epiblast similarly gives off a tubular process, which forms the 

 recessus vestibuli. 



Elevations in the primitive vesicle indicate the origin of the 

 semicircular canals, which become tubular, opening at their ends 



FIG. 296. 



Transverse section through the head of a foetal sheep in the region of the 

 hind-brain. (Boettcher.) HB. Hind-brain, cc. Canal of the cochlea. RC. 

 Recessus vestibuli. VB. Vertical semicircular canal. GC. Auditory gan- 

 glion. G X . Auditory nerve. N. Connection of auditory nerve to the hind- 

 brain. 



into the general cavity of the vesicle. The two superior canals 

 are the first to appear, the horizontal canal rising somewhat 

 later. 



The part of the otic vesicle in connection with the canal of the 

 cochlea becomes separated from the latter by a narrow constric- 

 tion, which forms the canalis reuniens, the part of the vesicle be- 

 yond this developing into the saccule. 



