AND THE CRISTA SPIRALIS OF THE COCHLEA. 77 



externa," adhering or attached fibers. They take origin from the phalanges by two 

 limbs : 



"Bin innerc Schcnkcl ist von einein aiisseren bei diescm zweispaltigcn Ursprung dcr 

 Haftfasern der I und II D. Zellen zu unterscheidcn, von dencn sich jeder aus einer Summe 

 von Fibrillen sammelt, vvelche auf die beiden entgegengesetzten und brciteren Ecken der 

 Phalangen-platten hauptsachlich verteilt sind, wenn auch eine geringe Anzahl auf dem 

 schmaleren Mitteil stehen kann" (p. 221). 



The double lines or double filaments of Held's figure 15 and the coarse fibers 

 in his figure 16 are undoubtedly the same elements as my lines /, figure 29, which 

 I regard not as fibrillar, but as bands or walls, homogeneous like the subjacent 

 membrana reticularis. 



It may be pointed out that, with N. Van der Stricht, I consider the mem- 

 brana reticularis of the organ of Corti as fenestrated and constituted by a system of 

 enlarged terminal bars separating openings within which the apices of the sensorial 

 and of the supporting cells are located. Held (1904) and others describe the apices 

 of the Deiters cells as a constituent of this membrane. 



The membrana tectoria of the kitten deserves special mention. Fixed by 

 osmic acid and Bouin's fluid or by trichloracetic acid it shows on its lateral edge a 

 regular series of coarse filaments, the thickness of which equals the diameter of the 

 apices of the third row of Deiters cells. Upon each of these apices is adherent a 

 thick, solid, long cylinder, a real cramp (un crampon), even where the entirely free 

 part of the membrana tectoria is detached from the organ of Corti. I am not able 

 to determine if these attachments persist in adult animals. The cramps mark 

 clearly the lateral boundaries of the membrane and of its anatomical substratum. 

 I have not, so far, had the opportunity of investigating the earliest stages of their 

 development, since I have at present no embryonic cat material available. It 

 seems to me that Retzius (1884) observed these elements in the cochlea of the cat, 

 since he described, in the Randfasernetz, "glanzenden parallel neben einander von 

 innen unt-en nach aussen oben verlaufende Fasern, wclche sich am Ausserrande zur 

 einem Randstrang sammeln. " 



ON THE SURFACE OF THE CRISTA SPIRALIS. 



All authors agree that the crista spiralis takes only a slight part in the develop- 

 ment of the membrana tectoria. According to my investigations, the alterations 

 of its superficial mosaic in the earliest stages of its activity are essentially the same 

 as those described for the greater epithelial ridge, although thinner terminal bars 

 and larger cytoplasmic fields result in some differences. Figure 28 shows that the 

 most superficial layer of the tectorial membrane, first developed and visible on the 

 right of the figure (mtcr), is formed by a system of larger fields and thinner inter- 

 mediary membranes than those belonging to the neighboring segment (mtg) of the 

 greater ridge. But in a layer a little deeper and more to the left the wide areas 

 disappear, because a kind of delicate network covers them. Finally, still more 

 to the left, the membrana tectoria of the crista spiralis exhibits the same structures 

 as those of the greater epithelial thickening. 



