METHODS FOR PREPARING THE ORGAN OP CORTI. 377 



&c., will break away on an attempt being made to cut 

 the cochlea longitudinally, and sections will be obtained, 

 in which nothing can be seen but the limbus and an at- 

 tached fragment or two of the broken niembrana basilaris 

 adhering on the one side to the base of the limbus, on 

 the other to the ligamentum spirale. To make satisfac- 

 tory preparations, the turns of the cochlea must be filled 

 with imbedding substance, to act as a support to the delicate 

 structures during the cutting operation, and this must be 

 removed from the section before it is finished. A substance 

 is thus required which shall be both firm and also be readily 

 dissolved away after it has done its part. The best for the 

 purpose is a mixture of equal parts of wax and cocoa butter. 

 The most effectual method for filling perfectly all the turns 

 of the cochlea is to place the organ in a small porcelain dish 

 full of the melted embedding substance, and to place the dish 

 under the receiver of an air pump, and exhaust till bubbles 

 cease to come from the floating cochlea and it sinks. The 

 dish may then be taken out, and there will be time before 

 the contents set to arrange the cochlea in a suitable position. 

 The mass, when cool, may be removed from the dish by 

 warming slightly the bottom of the latter, and may be cut 

 into a convenient shape for holding in the hand. 



Vertical sections of the entire cochlea may now be cut 

 with the razor, and should be floated at once off the razor on 

 to glass slips by means of alcohol dabbed on to the razor with 

 a brush behind them. Serviceable sections will not, of 

 course, bear handling with needles or lifting. The hollow 

 turns of the cochlea exposed in the sections are filled with 

 the imbedding substance. To remove this the sections must 

 be treated on the slide with turpentine or benzoine, best 

 slightly warmed. As soon as the matter is all dissolved 

 away, Avhich fact can be ascertained by placing the slides 

 under a low power, the sections should be treated again 

 with absolute alcohol to remove the turpentine. A drop of 

 simple aqueous solution of carminate of ammonium should 

 be put to each section, which will be sufficiently stained in 

 from five to ten minutes. The sections should then be washed 

 with a drop of water, all moisture removed from the slide by 

 tipping it and wiping with a cloth, and then absolute alcohol 

 should be again applied. When all water has thus been 

 removed from the section a drop of oil of cloves should be put 

 to it ; and as soon as it is thoroughly transparent a drop of 

 Dammar varnish may be substituted for the oil of cloves, and 

 a thin glass cover put on. Some sections may also be mounted 

 without carmine staining, the chromic acid staining being 



