ACTION OF THE TECTORIAL^' MEMBRANE 



487 



difficulties of construction involved. It was decided that such 

 evidences of vibration as could be obtained with the cochlea 

 represented as a straight canal would be suggestive of actual 

 activities though perhaps simpler. 



The two scalae are relatively larger in the human cochlea than 

 in those of the hog, beef and rat. 



Fig. 4 Outline drawing of a vertical section of the cochlea of the adult hog 

 showing variations in the scalae vestibuli andtampani and in the proportions of 

 the tectorial membrane. For meaning of reference letters, see page 478. 



Figure 5, A, is a line drawing of the model entire with the 

 accessory parts attached as used in most of the work with it. 

 Figure 7, A, shows that end of the model which represents the 

 basal end of the cochlea and figure 6 represents in detail a trans- 

 verse section of the model. 



For the labyrinth of the cochlea, three pieces of wooden board 

 1 J inches thick and 44 inches long were so cut and joined together 

 as to make a water-tight trough with inside dimensions of 2j 

 inches square and 42 inches long when the ends, cut from the 



