38 ANATOMICAL AND PHYSIOLOGICAL STUDIES ON 



Kolliker ('67) finds the membrane 45 n thick in the ox. In 

 the guinea-pig it is 15 ^ in the thickest place, according to 

 Schwalbe ('87). Middendorp ('67) gets in mammals generally 

 a very thin membrane, about 1 n thick. Retzius ('84) states 

 that in the thickest part in the rabbit it measures 27 [x, in the 

 cat 32 to 50 |x, and in man 24 to 25 [x. Hardesty finds in the 

 young pig an average thickness of the teased membrane of 

 50 [x and in an adult hog 119.3 (x. I get 35 (x as an average in 

 the adult albino rat after twenty days of age, varying from 32 

 to 38 [x. My result is therefore closest to that for the cat as 

 obtained by Retzius. These results are plainly influenced b.y 

 the dissimilar technical methods used by the several investigators. 



About the outermost end of the membrane there are still two 

 different views. One view is that the outer end of the membrane 

 projects beyond Hensen's prominence; Kolmer ('07; pig, calf 

 goat and horse); Hardesty ('15; pig, hog) Shambaugh ('10; pig). 

 Others assert that the membrane terminates with its outer edge 

 at the outer boundary of the outermost series of the outer hair 

 cells. My preparations show that in the rat the outer end of 

 the membrane does not reach Hensen's prominence. 



Possibly this difference is due to the technique of preparation. 

 In the figures drawn by many authors we can recognize many 

 artifacts and postmortem changes in the cochlea. Even in the 

 figures of Kolmer ('07) we see these changes, although he injected 

 the fixing solution through the carotid artery. Held ('09) says 

 in his criticism of Hardesty 's figures that " figures 6 and 7 wie 

 schon Hardesty selbst vermutet hat, sicherlich auf einer Ver- 

 quellung beruhen " 



I myself never observed such a gigantic membrane as Hardesty 

 ('08, '15), Shambaugh ('10), and others show in the cochlea 

 of the pig. On the other hand, I cannot absolutely deny that 

 there may have been shrinkage in the cochleas prepared by my 

 methods, though I see no evidence of it. 



From our present knowledge, however, the method of vital 

 fixing is considered the best available, as already maintained by 

 Siebenmann and Yoshii ('08), Metzner and Yoshii ('09), Nager 

 and Yoshii ('10), Wittmaack and Laurowitsch ('12), and others. 



