PROPORTIONS OF THE TECTORIAL MEMBRANE 7 



the fixing fluid which was used chiefly here (see below) for fixing and 

 decalcifying. He describes the tectorial membrane of the rabbit as 

 composed of three layers in thickness and, during development, three 

 zones in width. In the mature stage, he thinks the third or outer 

 zone is questionably distinguishable, and that the only attachment of 

 the membrane is that of its axial edge, or inner zone, upon the vestib- 

 ular lip of the spiral limbus, the entire outer part being free. Cer- 

 tain of the findings in Held's paper will be referred to in place. 



Vasticar ('09 and '10) gives what purports to be a study of the 

 tectorial membrane from fresh and osmic acid fixed cochleae of the rab- 

 bit. As far as the anatomy of the membrane is concerned, beyond 

 the statement that it is a "cuticular membrane of extreme delicacy," 

 his descriptions of vertically implanted, independent filaments, like 

 a vertically placed hair brush, the ends of the filaments sometimes 

 showing an 'olivary corpuscle,' that the ends of the filaments give the 

 basal surface the appearance of spiral striations, etc., are so far from 

 structure actually observed and so fanciful as to render his conclu- 

 sions worthless. He agrees with Coyne and Cannieu ('95) that 

 the outer zone of the membrane is attached to the spiral organ, united 

 by short cuticular ligaments to its cells as far over as the cells of Hen- 

 sen, and he cites Corti, Claudius, Henle and Lowenberg as supporting 

 this attachment of the outer zone, but states that Waldeyer, Hensen, 

 Ranvier, Retzius, M. Duval, Tafani and others claim there is no attach- 

 ment of the outer zone. 



Prentiss ('13) deals with the cochlea of the pig, using stages from 

 4 cm. in length up to fetuses at about full term. He advances one 

 new claim. The initial purpose of his paper seems to have been to 

 support the frequently made assumptions of Shambaugh ('07, '08, 

 '10, and '11) and to demolish by controversy suggestions offered by 

 others as to the actual anatomy and probable action of the tectorial 

 membrane. He states his best results were obtained b}^ fixing with 

 2 per cent osmic acid and with vom Rath's osmic-picric-acetic mix- 

 ture, claiming that the precipitation of the reduced osmium tetroxide 

 gave a browning of the tectorial membrane by which "its cuticular 

 structure" was sharply brought out. He decalcified before embed- 

 ding with 5 per cent nitric acid in 80 per cent alcohol and used celloidin 

 sections. A certain amount of decalcification must have been accom- 

 plished while in vom Rath's fluid. Later in his paper he refers to hav- 

 ing dissected out tectorial membranes by "more favorable methods" 

 than those employed by me and with results which did not support 

 my observations. While in my first experiments in teasing out the 

 fresh membranes I did "crush the bony labyrnth with a hammer," 

 this was not done later and in doing it I doubt that the cochlea was 

 jarred much more than by breaking the bone in another way, nor do 

 I think that, as assumed by Prentiss, the blows necessarily disturbed 

 the normal attachment of the membrane much more than consider- 

 ably heavier blows on the skull which the function of hearing is able 

 to sustain. While Prentiss's methods of dissection could have been 



