DEVELOPMENT OF THE ORGAN OF CORTl 285 



desty ('15, p. 52) states: ''The normal spaces between the 

 elements of the spiral organ, including the large Nuel's space, 

 no doubt result in part from this movement of the organ axis- 

 ward." Other authors, Rosenburg ('68), Boettcher ('69), and 

 Pritchard ('76) describe two neighboring inner and outer pillars 

 as derived from a single original cell, the nucleus of which divides 

 in two, and by a process of liquefaction of the undivided cyto- 

 plasm, the tunnel space is produced within it. This space is 

 originally intracellular and its fluid is a protoplasmic product. 

 Rickenbacher ('01, p. 402) seemingly ascribes a similar origin to 

 the fluid of the space of Nuel in the adult guinea-pig : ' ' Bei der 

 Schnecke des ausgewachsenen Tieres hat der Prozess der Ver- 

 fltissigung zur Bildung des Nuelschen Intercellularraume und des 

 Leiterepithels gefiihrt." According to Kishi ('02), the tunnel 

 space is due to the spiral course of the nerve fibers after they 

 have passed through interstices between the inner pillar cells. 

 The formation of tunnel and intercellular clefts is considered by 

 Held ('09) to be the result of 'ungleichen Wachstumbewegungen' 

 of different epithelial cells. His so-called 'outer tunnel,' the 

 spaces between the outer hair cells, and the space of Nuel out- 

 side the outer pillars are sheer intercellular channels, 'reine 

 Intercellularspalten;' but the tunnel between the pillars is 

 originally intracellular. 



Eine reine intrazellular Spalt, da die ersten Nervenfasern, die hier 

 spiralig abbiegen und weiter ziehen, nicht in der Zwischengrenze 

 zwischen Aussenr und Innenpfeiler liegen, sondern im Protoplasma 

 der Innenpfeilerzellen randstandig eingebettet sind, was audi fiir die 

 unten den inneren sowie ausseren Haarzellen resp. zwischen den Dei- 

 terschenzellen imd in ihren Intel zellularbriicken gelegenen Formation 

 eines intraepithelialen Nervusplexus gilt. 



The development of the tunnel and the pillar cells is closely 

 connected wdth the formation of the pillar heads, the appearance 

 of the 'head-plates' of the inner pillars, the phalanx processes 

 of the outer pillars, and the extension of the membrana reticularis. 

 The superficial structures of the rods of Corti in adult mammals 

 have been exhaustively investigated by many observers: Max 

 Schultze ('58), Koelliker ('59), Boettcher ('59, '72), Deiters ('60), 



THE JOURNAL OF COMPARATIVE NEUROLOGY, VOL. 30, NO. 3 



