DEVELOPMENT OF THE MEMBRANA TECTORIA 



447 



The membrana is undeniably shrunken and partly pulled away 

 from the spiral organ, but the hairs of the outer auditory cells 

 are firmly imbedded in the membrana. The under surface of 

 the membrana shows a thickening, st.H., which according to 

 Shambaugh ('08) corresponds to Hensen's stripe and represents 

 the inner line of its attachment to the inner supporting cells. 

 In other sections the membrana was firmly attached to the inner 

 supporting cells as well as to the hairs. In all of my prepara- 

 tions at full-term the membrana was badly shrunken. Frequently 



R.COC 



Fig. 10 Section through the apical turn of the cochlea at about full term, show- 

 ing outer auditory hairs imbedded in the membrana tectoria; ep.s.sp., epithelium 

 of spiral sulcus; i.h.c, inner hair cells; i.^il., inner pillar; m.has., basal membrane; 

 m.tect., membrana tectoria; lab.vest., labium vestibulare; limb.sp., limbus spir- 

 alis; n.coch., cochlear nerve; o.h.c, outer hair cell; sc.tymp., scala tympani; 

 s.sp., sulcus spiralis. Oc. 4, Obj. 4, t. 1. 190. 



also the organ of Corti was distorted, being pulled inward by the 

 attached membrana. 



The attachment of the membrana to the spiral organ I regard 

 as normal for the following reasons: 



1. In development the membrana is normally so attached. 



2. The auditory hairs when attached could be traced into the 

 membrana, even though the latter was badly shrunken. 



3. The shrinking membrane frequently exerts such a pull upon 

 the spiral organ as to distort it. 



