ON THE PROPORTIONS, DEVELOPMENT AND 



ATTACHMENT OF THE TECTORIAL 



MEMBRANE 



IRVING HARDESTY 



From the Department of Anatomy, Tulane University of Louisiana 



ELEVEN FIGUKES 



Some years ago the writer (Hardesty '08) made an attempt 

 to present something of the actual nature of the mammalian 

 tectorial membrane based chiefly upon the study of teased fresh 

 and unshrunken specimens. After learning something of the 

 nature, shape and proportions of this structure in the fresh con- 

 dition as compared with its appearance in the more usually 

 employed sections of the cochlea, the writer became convinced 

 that of the very numerous observations upon the membrane 

 previously published practically all had been based upon the 

 various more or less abnormal, rather than normal, appear- 

 ances of it produced by the methods of its preparation for study. 

 Experiments as to the action of the commonly used reagents 

 upon the fresh tectorial membrane showed that under the usual 

 treatment with alcohol in dehydration and the action of clear- 

 ing reagents it suffers far more shrinkage and distortion than any 

 other structure in the cochlea and perhaps in the entire body. 

 This result of dehydration and clearing was very evident even 

 after the action of fixing fluids which themselves were found to 

 produce but little distortion. For this reason it was concluded 

 that the usual sections of different embedded cochlea, and often 

 different sections of the same cochlea, show the membrane, even 

 in a given locality of its coil, varying greatly in its shape, size and 

 in its position over the spiral organ (of Corti). The hope then 

 suggested itself that something might be contributed to the 

 knowledge of the actual character, shape and proportions of 

 the tectorial membrane by studying it in the fresh condition, by 



THE AMERICAN JOURNAL OF ANATOMY, VOL. 18, NO. 1 

 JUI V, 1915 



