276 PRACTICAL HISTOLOGY. 



branous bag the saccule and both contain a white, 

 pasty, cretaceous, otolithic mass, which lies over the 

 part to which the nerve proceeds. ISTear one of the 

 attachments of each semicircular canal to the utricle 

 is its dilated part, or ampulla, and a branch of the 

 auditory nerve may be seen proceeding to each of 

 these, and terminating abruptly in a forked thicken- 

 ing, which indents the membranous wall and lies 

 transversely to the axis of the ampulla. 



The three ampullae, and the adjacent portions of 

 the semicircular canals, are now to be removed from 

 the cavities containing them, and are to be placed, 

 one in a weak solution of chromic acid (-J- per cent.), 

 one in osmic acid (2 per cent.), and the third on a 

 slide in a drop of endolymph obtained from the 

 cavity of the utricle. The piece in chromic acid is 

 transferred to weak spirit after three days, and in 

 twenty -four hours more to strong spirit. After 

 another day or two it may be placed in Kleinen- 

 berg's logwood for several hours, and then embedded 

 either in wax-mass in the ordinary way, or by the 

 cacao-butter process. Sections are to be made both 

 of the semicircular canal proper, and of the ampulla, 

 opposite to and including the entrance of the nerve ; 

 and the sections are passed through oil of cloves, 

 and mounted in dammar. The piece in osmic acid 

 is transferred after twenty-four hours, first to water 

 for two or three hours, and then to spirit ; after a 

 day or two in this it may be placed in oil of cloves, 

 and subsequently permeated with and embedded in 

 cacao-butter. The sections, after the cacao-butter 

 has been removed by oil of cloves, and this again 

 by spirit, are finally mounted in glycerine. The 

 third piece, especially the part where the nerve 

 enters, is broken up at once in the drop of endo- 

 lymph, and examined with a high power, with the 

 view of observing the two kinds of epithelium cells 

 columnar and spindle-shaped which occur here, and 

 the stiff, hair-like projections which are attached to 



