300 O. VAN DER STRICHT 



horizontal bundle (op/i'^) and is outlined by a thinner apical 

 border or wall, and a larger basal border, the bulk of the head. 

 On penetrating into the head the fibrils of the pillar body (opb) 

 become divided into two fasciculi, a thinner apical, and a broader 

 basal one. The fonner seems to be shorter and its fibrils spread 

 out obliquely through the corresponding lip; the latter is longer 

 and its fibrils spread out fanlike (fig. 15, ohd) through the basal 

 portion of the head, and seem to encroach upon the more homo- 

 geneous head roof. When the two systems of fibrils are not 

 stained, the head roof can be more clearly seen to continue into 

 the two borders of the notch. In the cochlea of young animals 

 (fig. 10, ohd) the groove is much larger and its lips may be mis- 

 taken for sections through two different separate bodies, the 

 'ellipsoider Einschlusskorper' of Schwalbe and Joseph. These 

 bodies do exist in earlier stages of development, but later, with 

 the roof, they form one structure — the head cap. 



The elongation of the phalanx process of the outer pillar will 

 be dealt with in the next chapter. 



The development of the spaces of Nuel. 



With the exception of very short references, such as those 

 alluded to above, no investigations have been carried out to 

 determine the formation of the spaces of Nuel. Fence the 

 problem appears to be a very knotty one and abiiost insolvable. 



In the cochlea of adult animals the largest of these spaces is 

 represented by a spiral cleft between the outer pillars and the, 

 cell bodies of the hair and supporting cells of the first outer 

 row. This space may be termed the first space or the first 

 spiral interstice of Nuel. Another cleft, which may attain 

 considerable size, is the fourth space or spiral interstice of 

 Nuel. This contains the phalanx processes of the cells of 

 Deiters of the third row and is included between the hair cells of 

 the third row and the so-called cells of Hensen. It is the 'ex- 

 ternal tunnel' of Held ('02). A second and a third space or 

 spiral interstice of Nuel contain the phalanx processes of the 

 cells of Deiters of the first and second rows, respectively, the 



