304 O. VAN DER STRICHT 



covered by the equidistant bundles and the lateral part of the 

 uninterrupted striated membrane, formed of the head plates of 

 the inner pillars. This description is corroborated by vertical 

 spiral sections. In figures 14 and 15, above the heads of the 

 outer pillars (ohd), is seen a dotted, very delicate membrane 

 {ipl"), subdivided into short segments by coarser spots. This 

 is the fibrillated membrane formed of the head-plates of the 

 inner pillars ; the fibrils have been cut transversely and the spots 

 represent the sections of terminal bars which separate the 

 plates. This dotted membrane extends over the neighboring 

 space of Nuel {SN') and covers equidistant coarse granules 

 (op/i'^'), the cross-sections of the phalanx processes of the outer 

 pillars. In figure 15 is seen, above the dotted line, a very fine, 

 pale, uniform covering, which doubtless represents the homo- 

 geneous superficial zone {ipl') already mentioned. 



The phalanx process of the outer pillar, represented in early 

 stages by two portions, is formed in the adult cochlea of three 

 segments, the original two — a subphalanx (fig. 13''', oph') and an 

 intercellular segment (oph'') which courses between two hair 

 cells— and a subsequently developed one, the submembranous 

 stalk {oph''') which is derived from a part of the original intra- 

 cephahc bundle (fig. 11, oph'''). Indeed, transitional stages 

 can be observed. In figure 11 an uninterrupted extracephahc 

 clear protoplasmic layer, a kind of a pale veil, developed from 

 the embryonic heads of the outer pillars (fig. 8, ohd) by a proc- 

 ess of differentiation, unites three upper fasciculi (fig. 11, 

 oph''') and assumes a festooned appearance around three lower 

 bundles. This festooned appearance has been observed by N. 

 Van der Stricht in the cochlea of a guinea-pig one day after 

 birth. This investigator described (p. 641) each festoon as 

 ''une sorte de voile triangulaire a sommet dirige vers la rangee 

 des cellules acoustiques externes et a base en continuity avec la 

 tete du piUer externe," and beheves that the veil corresponds to 

 the "Schwelling des Aussenpfeilerschnabels" of v. Spee. This 

 clear protoplasmic sheath of the extracephahc bundle is seen 

 also in vertical spiral sections (fig. 10, oph'''). In the cochlea 

 of a dog about four or five months of age it seems to persist, 



