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C. W. PRENTISS 



4. Physiologically and anatomically it is the condition we 

 should logically expect if the menibrana is functional in trans- 

 mitting sound waves to the auditory hairs. 



5. Were the membrana merely floating in contact with the 

 hairs and unattached to them or their supporting cells it would 

 not retain its position constantly and would thus interfere with 

 the auditory function. 



In describing the structures of the cochlea the apex is regarded 

 as above, the base as below and the membrana tectoria as lying 



Fig. 11 Dissection of the head of a pig fetus to show the position of the brain 

 and cochlea. X 4. 



over the spiral organ. As a matter of fact when in its normal 

 position the apex of the cochlea is directed cephalad and ven- 

 trad. This may be well seen in a dissection of the brain and 

 cochlea of the pig (fig. 11). 



When the pig's snout is directed downward, as in feeding, the 

 base of the cochlea would be above, the apex below. The same 

 would be true of the human cochlea when the head is bent for- 

 ward. The membrana tectoria would then he beneath the spiral 

 organ and as it is slightly heavier than the endolymph and very 



