The Nature of the Tectorial Membrane 169 



including the basal coil. Greater amplitude would mean intensity of 

 impingement and interpretations of intensity of sound. Physical rein- 

 forcement of wave motions would mean reinforcement of tones; quality 

 of impingement upon the auditory hairs would mean quality in the 

 sensations as interpreted; the number of a given variety of stimuli 

 applied to the unit area of hair cells would determine the predominant 

 variety of the sensations resulting. 



If the accessory tectorial membrane described in previous pages of 

 this paper should prove to be a true and constant structure, it would be 

 considered capable of separate vibration. Varying slightly in width, 

 being narrowest at the basal end, this membrane suggests a considerable 

 increase in the possibilities of function of the cochlea. It would undu- 

 late in accord with waves in the endolymph too faint to agitate the 

 main body of the membrane at all, while its vibrations would be subject 

 to the same conditions and would vary much as those of the main body. 

 With waves of greatest amplitude it would act in conjunction with the 

 main body. It is interesting to note that from its position it would act 

 alone, only upon the outer and wider series of the auditory hairs. 



In all the preparations showing the coherent series of the outer 

 rods of Corti's organ, an interesting interrelationship of the rods was 

 suggested. As seen on the flat, the shafts or slender mid-portions of 

 the rods invariably showed a tendency to be grouped (Fig. 13). From 

 those preparations in which the locality of the coil could be determined, 

 this grouping seemed to be different in different regions. In the first 

 turn of the organ of Corti, the shafts were grouped in twos and threes; 

 in the second turn (Fig. 12) they were grouped in threes and fours; 

 in a longer strip of them, fully five millimeters, which, during the 

 teasing process, was seen to float out from the region of the fifth turn, 

 the shafts were arranged in groups of from five to eight. None were 

 obtained as coming from the basal coil. 



We have no information as to whether or not the rods stand in this 

 relation during life. They possibly stand straight and equidistant and 

 cohere into groups during the manipulation before and during the 

 mounting on the slide. In forming the arch bounding the tunnel of 

 Corti, the shafts of the rods stand approximately straight in profile 

 view, while the portions braced by the foot-cells always curve as they 

 approach their rest upon the basiliar membrane (Fig. 12). It was 

 thought possible, then, that the grouped appearance of the shafts on 

 the slide might result from the straightening of the curved foot-portion 



