THE INTERNAL EAR 



621 



extremity a single tuft of long cilia, having the appearance of a 

 delicate hair-like process which projects into the endolymphatic 

 cavity. That portion of the endolymph which immediately over- 



^Uassrai 



^ & 



tfTS 



G ; S> ( 



iVa&M". 





FIG. 452. TRANSECTION OF THE MARGIN OF THE MACULA SACCULI OF A GUINEA-PIG. 



a, otolithic membrane; i, cilia; 0, cuticular membrane; d,hair cells; e, sustentacular 

 cells ; /, epithelium of the saccule ; <7, tunica propria ; A, nerve fibres ; *, bone. Hema- 

 toxylin and eosin. x 325. (After Kulliker.) 



lies the macula, and into which the hair-like processes project, 



though not essentially different in microscopic appearance in fresh 



tissues, appears to possess a somewhat gelatinous consistence, and 



in it are suspended various 



forms of crystals of calcium 



carbonate which are known as 



otoliths. The free surface of 



the neuro-epithelium is also 



provided with a reticulated 



cuticular membrane which 



presumably is formed by the 



amalgamation of the free ends 



of the sustentacular cells. 



Through the openings in this 



reticular membrane the ciliary 



tufts of the hair cells project. 



The central ends of the hair cells, beneath the nucleated 

 enlargement which is found near the middle of the epithelial layer, 



FIG. 453. NERVE ENDINGS IN THE MACULA 



OF A GUINEA-PIG. 



a, epithelium ; 5, tunica propria ; c, three 

 terminal nerve fibres. Golgi stain, x about 

 200. (After Ketzius.) 



