464 H. M. BERNARD. 



of the rods, as if in the act of being absorbed. Hence it is 

 but natural to assume that some of the refractive matter 

 which later fills these vesicles to overflov^^ing should early find 

 its way into the tips of the cones and be squeezed out by 

 the lateral pressure described in Part I as existing in the rod 

 layer, so as to appear as refractive globules just above the 

 line where the pressure of the rods ceases, i. e. on a line 

 between the junctions of the inner and outer limbs. The 

 secondary thrusting back again of these globules in cones 

 (cg), described in Part I of this paper, needs no comment. 



Then, again, I mentioned in Part I that in young tadpoles 

 it was possible at times to see these globules actually dis- 

 appearing in the ellipsoids of young rods (see PL 3, fig. 15), 

 showing clearly that, in this refractive globule of the cone 

 with its adjoining staining matter, we really have the ele- 

 ments of the future ellipsoid, though not blended together. 

 Further, in one of my slides of a young frog tadpole the 

 refractive matter absorbed by the rod is not always dis- 

 coloured ; globules of bright reddish-brown matter exactly 

 resembling the pigment in colour occur high up in the rod, 

 near the transverse membrane, while as a complete confirma- 

 tion of the argument, globules of exactly the same colour 

 can here and there be found in the ellipsoids of the same 

 rods. 



The condition found in the cones of the frog thus helps us 

 to understand the ellipsoid in the cones of the other Am- 

 phibia here dealt with. It has long been known that the 

 refractive globule was absent from the cones of the toad, an 

 absence which was disconcerting to the earlier investigators, 

 who would attribute to it an important dioptric function. It is 

 also absent from the cones of the salamander and the axolotl. 

 In these cases, from our point of view, it is not so much that 

 the refractive matter is absent, but that it never really forms 

 as a distinct globule ; it is mixed with the staining matter to 

 become the ellipsoid as fast as it collects. 



In the case of the newt, all students will remember that 



