230 PEACTICAL HISTOLOGY [XXX 



2. Place a fresh ampulla in osmic acid *5 p.c. for 

 about half-an-hour (or longer), treat it in the mariner 

 given in Less. XII. 1, b. observe the nerve fibres 

 with blackened medulla in the wall of the tube and 

 the shape of the isolated cells. 



3. The cochlea. Section of the cochlea 1 of a 

 guinea-pig or other mammal cut parallel with the axis 

 of the modiolus. Observe 



The division of each turn of the cochlea into three 

 canals by the basilar membrane running across from 

 the end of the lamina spiralis, and by the membrane 

 of Reissner starting from the lamina farther back ; 

 the latter may have been torn through. 



The following modifications of the epithelium cells 

 of the scala media, starting from the inner side of the 

 basilar membrane. 



a. Cells passing from cubical to columnar. 



b. The single inner hair cell, columnar with 

 short hair-like processes, the so-called hairs arising 

 from its free surface ; its deep pointed end is more or 

 less hidden by small cells with large nuclei. 



c. The inner and the outer rod of Corti. 



d. The three or four outer hair cells, long 



1 Cochlea in Flemming's fluid 8 to 24 hours (expose in one place 

 the cochlear canal), water 1 day, decalcify in 75 p.c. alcohol con- 

 taining 1 p.c. nitric acid, water 1 day. Stain in bulk with acid 

 hflematoxylin, or alum carmine, or stain the sections on a cover-slip 

 with Benaut's eosin-hsematoxylin, 



