1030 ORGANS OF THE SENSES AND THE COMMON INTEGUMENT 



then closed, and thus a shut sac, the auditory vesicle, is formed (Fig. 899); frcm it 

 the epithelial lining of the membranous labyrinth is derived. The vesicle becomes 

 pear-shaped, and the neck of the flask is obliterated (Fig. 900). From the vesicle 



Neural tube Endolymp Laferal groom 



Endolymph 





Vestib. 



Vestib. P uch 

 '''pouch 



d. sc. sup. 



4-8 mm. front 



absorpt. fvcu. 



Coch. pouch 

 6.6 mm. lateral 



d. sc. post. 



Lateral groove 



d. sc. lat. 



^'Cochlea 

 9 mm. lateral 



13 mm. lateral 



20 mm. lateral 



30 mm. lateral 



FIG. 900. Lateral views of membranous labyrinth and acoustic complex. X 25 dia. (Streeter.) absorpt. focu, 

 area of wall where absorption is complete; amp., ampulla membranacea; crus, cms commune; d. sc. lat., ductus semi- 

 circularis lateralis; d. sc. post., ductus semicircularis posterior; d. sc. sup., ductus semicircular superior; cock, or cochlea, 

 ductus cochlearis; duct, endolymph, ductus endolympnaticus; d. reunions, ductus reunions Henseni; endol. or endolymphs 

 appendix endolymphaticus; rec. utr., recessus utriculi; sacc., sacculus; sac. endol., saccus endolymphaticus; sinus utr. lot., 

 sinus utriculi lateralis; utric., utriculus; icstib. p., vestibular pouch. 



certain diverticula are given off which form the various parts of the membranous 

 labyrinth. One from the middle part forms the ductus and saccus endolymphaticus, 

 another from the anterior end gradually elongates, and, forming a tube coiled on 



