14 UNIVERSITY OF MISSOURI STUDIES 



means, because a mistake made here in our comprehension 

 of the process would result in serious errors later, that the 

 bulging of the partition, whether up or down, begins in- 

 evitably as near the two windows as possible, and that fur- 

 ther pieces can bulge in either direction only under the 

 condition that all the pieces nearer the windows have already 

 reached their limit in that same direction. 



We made at the beginning of the last paragraph the 

 assumption that there was a small opening between the two 

 divisions at the extreme end of the tube. 

 A safety valve Let us see what purpose such an opening 



could serve. What would be the result 

 of an extraordinarily large movement of the stirrup, so large 

 that the whole length of the partition would reach its — upper 

 or lower — limit of position before the stirrup ceased to move 

 in the same direction? The result would be either an enforc- 

 ed stop of the movement of the stirrup or, if the external 

 force acting on the tympanum and stirrup was too violent, a 

 bursting of the partition. The latter disastrous result, how- 

 ever, can to a considerable extent be guarded against by the 

 opening in question. As soon as the total length of the par- 

 tition has bulged the fluid will begin to flow through this 

 opening from one division of the tube into the other, until 

 the stirrup stops moving in the same direction. Such an 

 opening therefore can serve as a kind of safety valve for the 

 protection of the partition. 



After having studied the hydromechanical function of 

 several imaginary tubes with divers interior equipments, let 

 us now turn to a careful survey of the 

 The anatomy and ^ acts which the anatomists have discover- 

 physiology of ed for us concerning the structure of the 



the inner ear inner ear. Figure 7 shows us in a cross- 



section all the important details which have 

 been found there by the anatomists. Hard bone pro- 



