No. I.] THE VERTEBRATE EAR. gi 



figure a section through the sense organ of the sacculus, and 

 carry out a detailed comparison of the structures of the two 

 organs. The auditory club is physiologically equivalent to 

 the otoliths. Morphologically, however, the brothers Sarasin 

 think it is more like the cupula terminalis which Lang, Kuhn, 

 Hasse, and Kolliker, found in the ampullae of the ear. 



After thus briefly reviewing the history of the cupula ter- 

 minalis, we are better prepared to estimate the value of the 

 views which have been, and which in part are still held con- 

 cerning the tectorial membrane of Corti's organ or the auditory 

 damper of the physiologists. 



Its discoverer. Marquis Corti (185 1, 59), gave the following 

 account of it : " Quant on observe une bandelette dentelee dans 

 I'etat le plus frais et le plus intact possible, on voit que la mem- 

 brane tres mince qui lui sert de toit et tres tendue sur la ban- 

 delette meme et ne presente jamais aucun plis. Cette membrane 

 part, comme nous avons vu, environ du bord externe convexe de 

 la bandelette sillonnee en couvrant les dents de la premiere 

 rangee, et arrive a couvrir a peu pres trois rangees de cellules 

 epitheliales placees sur la zone pectinee," and he calculated the 

 distance between the " bandelette dentelee " and the membrane 

 to be about 0.0085'". 



Claudius (1855, 53) described Corti's membrane as a tolerably 

 tough, but extremely thin membrane, finely striated with parallel 

 markings ; to him it appeared elastic. It begins on the inner 

 border of the crista sulcata below the epithelium without apparent 

 boundaries, covers over the crista to the teeth, and from the 

 apices of the latter it stretches across to the periost of the outer 

 cochlear wall, running parallel with the membrana basilaris. It 

 inserts in the periost under the epithelial coat. It retains these 

 characters in all parts of the cochlea. 



Boettcher (1856, 29) wrote: "Corti's membrane stretches 

 parallel with the membrana basilaris from the acoustic teeth to 

 the inner surface of the outer cochlear wall, so that, together 

 with the basilar membrane, it forms a closed canal." 



Kolliker (1859, ^^7) • Corti's membrane is composed of (i) a 

 special striated lamella, (2) an epithelium, and (3) a delicate con- 

 nective tissue. The striated lamella appears to be of connective 

 tissue nature, is separable into a thinner and thicker portion. 

 The thinner is transversely fibrous, the thicker striated {i.e. 



