THE EYE OF I'ECTEX. 85 



which stain more distinctly, and it is probably these only 

 which fonn the "flange" and the attachment of rod-cells to 

 each other. 



The fibres are supporting fibrilho, and in preparations 

 wliere the rods had broken off (PI. 7, fig. 18ff) the tube of 

 fibrils could be distinctly seen. Where the rods remained 

 attached to the rod-cells the fibres were continued below the 

 thickenings, but had left the surface of the rod, enclosing 

 the latter in a kind of sheath (PI. 7, fig. 13). 



. Whether they lie on the rod-wall in the normal condition 

 or in the interstitial substance to be presently considered 

 I cannot say. Another point concerning the shape of the 

 rod-cells remains to be referred to. Above the nucleus the 

 rod-cell does not become gradually less in diameter, but after 

 a constriction there often occurs one or more irregular swell- 

 ings, which give the attenuated end of the rod-cell a more 

 or less varicose appearance. 



Patten saw one of these and described it as a delicate 

 oblong vesicle containing a second faintly staining and 

 often invisible nucleus. Pawitz would not consider the 

 presence of a nucleus, but saw the enlargement and said it 

 might be artificial. Schreiner also figures it. It is most 

 easily seen in isolated rod-cells, in a maceration. I find that 

 there may be one or more, and that they are simply due to 

 the rod-cell being flattened in places by the pressure of 

 adjacent cells; the flattened part appears as an enlargement 

 if not seen in edge view. 



The rods are cone-shaped with the apices rpuuded. The 

 base lias the same diameter as the rod-cell, that is, where 

 they are continuous, and from here the diameter gradually 

 deci'eases towards the lower end, though at first very gradu- 

 ally. They are separated and surrounded by a homogeneous 

 substance (PI. 7, fig. 13, R. mat.), which fills up all the cavities 

 that would otherwise have remained between them, and also 

 forms a layer below them. This substance is stained black 

 by iron htematoxylin, it is blackened by osmic acid, and is 

 stained blue by Mallory's connective-tissue stain. I believe 



