462 H. M. BERNARD. 



which case the body is usually an irregular flattened disc 

 (fig. 23). 



As a matter of fact, the body is of very various shapes. 

 Fig. 15 shows a series of cones and rods (salamander) in 

 which only in a young cone is the body egg-shaped, in others 

 it takes the shape of the tip of the swollen inner limb of the 

 cone : if the latter is large, the body is large ; if narrow, the 

 body is narrow, while in the definitive rod it is uniformly 

 plano-convex. It thus seems quite plastic in its earlier (cone) 

 stage, and only assumes a definite form in the full-grown 

 rod. 



Dealing, then, with this body as we have with the other 

 contents of the rod, we must regard it as an aggregation of 

 these contents which, for some reason or other, rests perma- 

 nently against the transverse membrane separating the inner 

 and outer limbs. 



It varies greatly in its staining. It is sometimes intensely 

 stained, at others it is comparatively clear and refractive. 

 In this latter case a dense stream of staining matter is very 

 frequently seen descending upon it from the nucleus (see 

 figs. 10, 23, 27). We cannot be far wrong, then, if we 

 refer the variation in the intensity with which the body 

 takes stain to the relative proportions of staining matter and 

 refi-active matter which compose it. For out of these two 

 substances, which, as we have seen, together constitute the 

 visible contents of the rods, it must surely consist. 



Regarding it for the moment in its definitive plano-convex 

 form, it seems to me that we have, both in its shape and in 

 its position, striking confirmation of our conclusion as to the 

 origins of the contents of the rod. On the one hand, we 

 have an outwardly streaming reticulum of staining matter 

 which, so far as we can see, only manages to get further, i. e. 

 into the outer limb by way of the outer walls. There cer- 

 tainly seems to be some condensation of the reticulum against 

 the blind end of the inner limb (see fig. 27, left-hand figure). 

 On the other hand, coming into the rods from the opposite 

 direction, viz. from the pigment epithelium, we have the re- 



