No. I.] THE VERTEBRATE EAR. loi 



somewhere between that of contracted muscle and adipose 

 tissues. It probably has the consistency of fresh brain tissue, 

 and is much more resistant than the cells of the ridge, which 

 have a consistency much like that of embryonic brain. Hensen 

 concludes that he is certain that the longitudinal fibres are 

 nerve fibres. He nevertheless admits that with the greatest 

 care it is oftentimes impossible to tell nerve fibres from proto- 

 plasmic processes. He could not find Nuel's fibres. 



Lavdowsky (1876, 178) : The hair cells have the hairs always 

 arranged in a horseshoe on the top of the cell. They are short, 

 glassy bacilli, often rounded on the end, which in the fully 

 grown animal are not organically connected with the membrane 

 of Corti. 



Lavdowsky found that some of the nerve fibres were not con- 

 nected with ganglion cells, and that some of the nerves, after 

 they had entered into the cochlear organ, end, not in the hair 

 cells, but in the ordinary epithelium of the zona pectinata. 



Corti's membrane begins near the root of Reissner's mem- 

 brane as a very thin structure, but rapidly grows thicker. It 

 extends with these relations through the whole of Corti's canal. 

 It covers over the sulcus spiralis, Corti's arch, outer hair cells, 

 and ends abruptly exactly over the last row of the outer hair 

 cells, having decreased somewhat in thickness from its middle 

 outward. Lavdowsky disagrees with Waldeyer that the mem- 

 brana tectoria begins in mammals or in man midway be- 

 tween the root of Reissner's membrane and the labium vestibu- 

 lare. Neither could he agree with Boettcher in this matter. 

 In silver preparations Lavdowsky always found the point of 

 origin very near Reissner's membrane. It can by no manner 

 of means extend beyond the outer row of hair cells. As the 

 membrane passes by the cells, it certainly does not enter into 

 the kind of union with them figured by Boettcher, but simply 

 applies itself closely to the hair cap of these cells. 



"As regards structure, the first and last zones, i.e. the inner 

 and outer, are homogeneous as I have found them, but I con- 

 sider the homogeneity of the first zone different from other 

 authors, since I find that the fibres of the middle zone narrow 

 themselves inwards and not outwards ; consequently the first 

 zone is merely a modification of the middle one, whose fibres 

 after narrowing: down fuse with each other into a continuous 



