110 Irving Hardesty 



siouallv held previously, that the tectorial membrane is the structure 

 acted upon by the transferred sound waves. Either view admits that 

 the hair cells are stimulated by impact or contact with the under surface 

 of the tectorial membrane. The very evident disagreement of these 

 papers in their descriptions and assumptions as to the character, form 

 and intimate structure of the tectorial membrane, and the fact that 

 none of the descriptions of the membrane seemed to apply correctly to 

 some preparations of the cochlea in the possession of the author, sug- 

 gested the undertakino; of the studv of the nature of that memln-ane. 



Materials and Methods. 



The material used for this study has been almost wholly obtained 

 from the pig, and all the illustrations given are made from the prepa- 

 rations of cochleffi of this animal. Preparations from other mammals, 

 including man, being obtainable with less ease and abundance, have 

 only been used for occasional comparison with the preparations from 

 the pig. 



Pig fcetuses of al30ut term, that is, from 26 to 30 centimeters, and a 

 litter of four pigs of about two weeks after Inrth were used. In all 

 cases, the heads Avere severed, the vault of the cranium and the enceph- 

 alon removed and the cochleoe then broken out from the inside and 

 made use of as soon as possible after obtaining the material. The 

 entire inner ear or bony labyrinth of the pig may be shelled out from 

 its lodgment in the temporal bone from the fact that osseous fusion 

 with this bone is of late occurrence. Kolmer, '07, mentions that even 

 in the adult hog the cochlea is not so firmly fused in the petrous part 

 of the temporal bone as it is in other mammals. 



All the published illustrations and all the ordinary laboratory prepa- 

 rations of cochleae agree in indicating one fact, namely, that the tectorial 

 membrane is invariably and badly shrunken and distorted by the action 

 of the usual reagents used in fixing, dehydrating, etc. Since the chief defi- 

 ciency of the papers describing the membrane appears to be failure to 

 determine and study its normal characters, it was deemed especially 

 necessary for the present study to obtain at least portions of it in the 

 fresh and natural condition. Attempts toward this end were first made 

 with frozen sections. The fresh cochlege were oriented and frozen on 

 the Bardeen Freezing Microtome and sections clipped into petri-dishes, 

 some containing normal salt solution alone, others 0.1 per cent methylene 



