AND THE CRISTA SPIRALIS OF THE COCHLEA. 71 



the former author, though his illustrations show undivided nuclear cytoplasmic 

 masses, speaks of "interdental cells;" the second mentions "nuclear bands." 

 Neither describes the syncytial nature of these formations. 



As a matter of fact, in many preparations some exceptions to this rule may be 

 found with spaces between the neighboring cells. I do not refer, of course, to figure 

 20, where the razor cut the teeth vertically just at the edge of the vestibular lip and 

 struck the epithelial cells of the subjacent sulcus spiralis, an unchanged columnar 

 epithelium (essp) ; I refer to figures which may be observed in the middle of the 

 limbus. Their existence proves that when the mechanical pressure is weak fusion 

 does not occur, or when it diminishes in adult stages boundaries may reappear. 



Do the numerous nuclei of this special kind of syncytium represent elements 

 of the primitive isolated cells? Or are new nuclei formed at the time of fusion of 

 the cell-bodies or afterward? As a matter of fact, after the first stage described 

 above, no mitoses occur within the epithelial cells. On the other hand, some prep- 

 arations seem to confirm the idea that occasionally nuclei undergo nuclear amitosis, 

 increasing in size and elongation, and exhibiting direct division into two smaller 

 daughter nuclei by a process of constriction. 



Retzius was able to investigate this question. His figures represent the super- 

 ficial mosaic with terminal bars stained black by silver nitrate; below each polygon 

 he notices a single nucleus, hence he asserts that there exist as many apices of cells 

 as nuclei, although near the vestibular lip some fields contain two nuclei which he 

 explains as due to the fact that the supplementary elements belong to the sulcus 

 spiralis. But by a careful examination of the figures of Retzius I can sometimes 

 count three nuclei beneath two superficial fields at a short distance from the vestib- 

 ular lip (his figure 1, plate 24) and also in the zona papillaris. 



If, in preparations similar to that displayed in figure 17, I compute the number 

 of superficial fields along one row of polygons of the zona dentata and the number 

 of nuclei of one nuclear band, I find that I obtain as a rule the same number (about 

 12) ; but there are some exceptions where there are one or two nuclei more than fields. 

 I am inclined, consequently, to believe that some occasional nuclei of the primitive 

 epithelial cells undergo the process of amitosis during the second or third stage of 

 development of the crista spiralis. 



Finally, I think that it is worth while to emphasize the fact that furrows men- 

 tioned by many authors between the prominences of the teeth, within which (ac- 

 cording to v. Winiwarter and others) nuclei or remains of epithelial cells are located, 

 do not exist at all. There are large interdental spaces completely filled by the 

 epithelial syncytial lamellae. In the adult organ the deep portion of these spaces 

 is broad, but the superficial gradually becomes very narrow at the level where the 

 cytoplasm is in continuity with the superficial mosaic. Superficial pits between the 

 teeth are either exceedingly small or are lacking; if they do exist they are covered 

 by only a part of the mosaic. The fused epithelial cell-bodies are embedded between 

 the teeth in such manner that I can not agree with Retzius (1884, p. 345) when (in 

 describing these conditions of the adult man) he states: " Diese Epithelzellen welche 

 sich beim Embryo als eine cylinderzellen Schicht anlegten sind also noch beim 



