236 bulletin: museum of comparative zoology. 



could be traced to the outermost ends of the sense-cells. Such free 

 terminations are shown in Figures 28, 33, 34, 36 (Plate 5). 



The most convincing evidence that the nerve fibres do not penetrate 

 to the interior of the sense cells, but pass between them, is afforded by 

 sections which lie in a plane parallel to the surface of the epithelium, 

 or nearly so. Figures 39 (Plate 5) and 44, 46-53 (Plate 6) represent 

 such sections. In Figures 44, 48 (Plate 6) the cut ends of nerve fibres 

 are shown. Such cut ends are always found to lie between the sense 

 cells and not within them. Sometimes they are in close contact with 

 the sense cells, and sometimes they are in the matrix of intercellular 

 material by which the sense cells are surrounded. In Figures 39 (Plate 

 5) and 48, 49, 53 (Plate 6) fibres are represented which make their 

 way between the cells of the epithelium. These conditions are typical, 

 and are in agreement with those seen in a large number of sections. 

 I have been able to find only two sense cells which appeared to be 

 exceptions to the statement that the sense cells do not contain nervous 

 material. These cells are shdwn in Figure 53 (Plate 6). In one of 

 them two fine filaments were discernible, as represented in the figure, 

 and in the other a ring-shaped body was present, which was connected 

 to an extracellular fibre. This latter structure at once calls to mind 

 the intracellular rings which Bielschowsky und Brlihl have figured 

 for the sense cells of mammals. Inasmuch as I have seen only one 

 example of such a structure, however, I am inclined to regard its 

 occurrence as the result of come accident, and to consider it as without 

 significance. 



In the series of sections which I have just been describing, which is 

 the single series in which the nerve fibres of the sacculus and lagena 

 appear to be completely impregnated and the non-nervous matter is 

 at the same time in good condition, there are many places where 

 delicate fibres may be seen in close proximity to the surfaces of the cells 

 (Figs. 39, Plate 5; 46-48, 50-53, Plate 6)". Not infrequently a fibre 

 divides at the surface of the cell, sending a branch to either side (Figs. 

 48, 50, 51, 53, Plate 6). One portion of the series, including a con- 

 siderable number of sections, when examined by the aid of an ordinary 

 high power objective, gave the impression that the sense cells are 

 completely surrounded in a meshwork of anastomosing fibres, which 

 mark the cell boundaries. When this material was examined under 

 the oil immersion, however, it was found that these fibres, like those of 

 the so-called subepithelial plexus of the crista acustica shown in Figure 

 13 (Plate 3), do not anastomose, but intertwine (Fig. 52, Plate 6). 



