308 O. VAN DER STRICHT 



size of the acoustic elements. The medial and lateral boundaries 

 of the fourth interstice of Nuel are represented, respectively, by 

 the lateral surfaces of the sensory elements of the third row and 

 the medial surfaces of the so-called cells of Hensen, which, ac- 

 cording to previous investigations, should be held as atrophied 

 hair cells {aoh'^'). 



The roofs of the spaces of Nuel are made up of parts of con- 

 tiguous apices of the supporting elements (fig. 9). The roof of 

 the second space is formed of alternating lateral and medial 

 segments of phalanges of the outer pillar {aop), and the Deiters 

 cells of the first row {d^). The roof of the third space is com- 

 posed of alternating lateral and medial segments of the phalanges 

 of Deiters cells of the first (d') and second row (rf'Ol the roof of 

 the fourth space is represented by the lateral segments of the 

 phalanges of Deiters cells of the second row and the apices of 

 those of the third (c?'"). The roofs of the intercellular clefts 

 between the hair cells of the first, second and third sensory 

 rows are formed, respectively, of the medial or constricted part 

 of the phalanges of the outer pillars (fig. 9, aop), the middle 

 part of those of Deiters cells of the first row (d'), and the middle 

 pari of those of Deiters cells of the second row (d^'). The fluid 

 contents of the first, second, third, and fourth spaces of Nuel 

 intercommunicate through the intercellular clefts. Like the 

 fluid of the first interstice, that of the others is separated from 

 the contents of the cochlear duct only by very thin membranes, 

 partially fibrillated, since the fibrillar bundles of the phalanx 

 processes of the sustentacular elements spread over the under 

 surface of their corresponding phalanx, according to the investi- 

 gations of Held ('02) and of N. Van der Stricht. Such struc- 

 tures doubtless are able to promote the propagation of vibratory 

 waves from the membrana basilaris to the fluid and the membrana 

 tectoria within the cochlear canal. 



