PROPORTIONS OF THE TECTORIAL MEMBRANE 39 



(and the cells of Claudius?), which zone he claims remains 

 permanently attached in the adult to the cells producing it. 



Held describes and figures for the rabbit fetus these tangled 

 fibrils arising from the lesser epithelial ridge and later attached 

 to the cells of the spiral organ, and calls them 'Haftfasern.' He 

 thinks that a part of his Decknetz and a narrow outermost zone 

 of the membrane is formed from them. In none of his figures 

 from the rabbit do his Haftfasern show an abundance and arrange- 

 ment similar to that of the membrane. On the contrary, his 

 figures for his fetuses up to near term, show what I consider the 

 outer edge of the tectorial membrane proper to terminate bluntly 

 at the axial side of the series of inner hair cells. He states that 

 his narrow outermost zone (formed from the fibrils in question) 

 is not distinguishable in the older stages and he thinks it a re- 

 trogressive structure, for later, when the whole outspamiing 

 zone of the membrane is becoming free, he finds only a thin 

 relatively coarse net upon the outer edge (selvage) of the 

 membrane. 



Rickenbacher, for the fetal guinea-pig, shows a mass upon 

 the lesser epithelial ridge, after the hair cells have differentiated, 

 considerably greater than I have seen in the pig. He described 

 it as of the nature of his granular, pale staining layer in which 

 fibrils appear, stating that in guinea-pigs of 5.5 cm., the tectorial 

 membrane proper ceases at the immediate axial side of the 

 inner hair cells and that the pale staining mass becomes a fibrous 

 'Deckschicht' upon and produced by the spiral organ, and that 

 it becomes a process of the tectorial membrane proper (p. 395). 

 In another place he states that it adds a small outer zone to the 

 membrane. It is later detached from the spiral organ, he agree- 

 ing that the outspanning zone of the developed tectorial mem- 

 brane of the guinea-pig is free. 



Prejitiss charges that I misrepresented Rickenbacher in using his 

 name as one who agreed that "there is no good reason to assume that 

 the cells giving rise to the organ of Corti ever have anything to do with" 

 the development of the tectorial membrane. In again going over Rick- 

 enbacher's paper, I find Prentiss' charge a true one, and I cannot con- 

 ceive of my reason at that time for using his name as I did in the sen- 

 tence quoted by Prentiss. It is barely possible that his name was 



