THE COCHLEA. 279 



tion of the modiolus occupies the axis from the base 

 to near the apex of the triangle, and on either side 

 are the sections of the successive spiral turns. Not 

 more than three or four complete axial sections can 

 l>e obtained from each cochlea. The razor and the 

 surface of the cake should be wetted with oil of 

 cloves instead of spirit. It may be applied by means 

 of a large camel-hair brush, and its use is that it 

 renders the parts more coherent, and tends to prevent 

 the organ of Corti from breaking away from the 

 basilar membrane, which it is otherwise apt to do. 

 The sections are examined, unstained, with a low 

 power, and if the organ of Corti is sufficiently com- 

 plete they are at once transferred to an alcoholic 

 staining fluid. One of the best is a weak solution of 

 acetate of rosaniline, but if this is not at hand, some 

 other aniline dye, such, for example, as eosin (see 

 Appendix), may be employed. When stained the 

 sections are again placed in oil of cloves, and finally 

 mounted in dammar. 



Preparations 5 and 6. Teased preparations 

 of the cochlea. Successful sections will show 

 the general position and relations of the rods and 

 other parts, and to a certain extent the individual 

 elements. But only a profile view can in this way- 

 be obtained, and since the minute structure of the 

 elements composing the organs of Corti can only 

 be properly seen when isolated, it is necessary to 

 prepare other cochleas with this object in view. 

 Another animal is accordingly sacrificed, and the 

 cochleas removed as before. One placed in a 2 per 

 cent, solution of osraic acid ; the other in a J per 

 cent, solution of bichromate of potash ; but, before 

 dropping them into their respective fluids, the bony 

 wall must be scraped through here and there with 

 a scalpel, so that the fluid "shall at once penetrate 

 to the interior of the turns. After two days the 

 cochleas may be further prepared in the following 

 way : 



The uppermost turn is broken or snipped off with 



