The Nature of the Tectorial Memljrane 125 



However, like the total width of the membrane, this inner, attached, 

 strip is narrowest in the basal tnrn and increases gradually, thougli 

 slightly, toward the apex to attain its greatest width in the first turn. 

 Owing to the extent and shape of the labium vestibulare at the ends 

 of the coil, this attached strip terminates in a point, and is the first zone 

 to terminate at the apex, while at the base it terminates bluntly rounded 

 and is the zone which persists farthest, wholly constituting the basal tip 

 of the membrane. 



Dupuis and others to be mentioned below, who studied the markings 

 on the under surface of the membrane, distinguished a boundary line 

 representing the outer extent of the labium vestibulare, or the boun- 

 dary of the zone of attachment upon it. Barth and Bottcher considered 

 this line an artifact. In all my teased preparations, but especially 

 those fixed in Zenker's fluid, this line was distinguishable and, from 

 further study, it is evident that Barth and Bottcher were correct in 

 considering it an artifact in so far that it only represents the impress 

 of the edge of the labium vestibulare, and has nothing further to do 

 with the structure of the membrane. Measurements of the attached 

 zone taken transversely to the inner edge of the membrane showed it 

 to vary gradually from 62.3 microns in the last half-turn to 87.2 

 microns in the first half-turn. 



These measurements subtracted from the total width of the membrane 

 at the same regions, give the free, outspanning portion of the membrane 

 a width of only 45.6 microns near the basal end, while the free portion 

 of the first half-turn attains a width of 219.9 microns. Ivishi, '07, who 

 studied the human tectorial membrane and that of a number of 

 common mammals, states that this outer portion (second zones he 

 calls it) is at least three times broader at the apex of the cochlea 

 than it is in the basal coil. He does not give measurements. In 

 Kolliker's Gewebelehre, Bd. 3, Second Half, Von Ebner states that the 

 tectorial, like the basilar membrane, is widest toward the apex of the 

 cochlea, and that, in man, the free portion has a width of 240 microns 

 at the apex, and 120 microns in the basal region. These figures indicate 

 that the free portion of the apical turn in man is only 2 times as wide 

 as that of the basal region, while the above figures for the pig show 

 the free portion in the first half turn to be 4.8 times as wide as it is in 

 the last. However, Yon Eben does not state at what particular portion 

 of the coil the measurements were taken nor whether they were made 

 from fresh or fixed specimens or from sections. Kishi, though he only 



