STUDIES IN THE RETINA. 465 



Max Schultze, and others after him/ described and figured a 

 combination of two "lenses," a biconvex and a plano-convex, 

 as a higher specialisation than the simple plano-convex "lens" 

 (the ellipsoid) of the frog, toad, salamander, etc. Max 

 Schultze even claimed that this lens could be isolated. The 

 body which he figured can be seen frequently enough, but 

 not by any means always in the shape of a biconvex lens. 

 It is nothing but a fluid vacuole, more sharply defined than 

 usual. Fig. 30 shows two rods of a newt side by side ; in 

 one there is a well-defined vacuole resting on the ellipsoid, 

 aud in the other a quite undefined vacuole like that usually 

 found in other Amphibia. The former is interesting because 

 its origin from the nucleus can be seen, a second one appear- 

 ing ready to escape. Most of the nuclei in this preparation 

 have vacuoles about the same size as shoAvn in fig. 30. 

 Further, in very many of the outer limbs of the rods rows of 

 fluid globules of different sizes can be seen. Compare the 

 views as to the origin of the fluid on p. 453. 



Let us sum up the conclusions so far arrived at, forbeai'ing 

 to enter more fully into the pliysiological results obtained 

 till the corroborative evidence yielded by the eyes of verte- 

 brates other than Amphibia can be prepared for publi- 

 cation. 



The rods in the Amphibia are specialised protrusions of 

 the retina, consisting of extremely delicate protoplasmic vesi- 

 cles, each divided by a transverse membrane into an inner 

 and an outer coinpartinent. The staining reticulum which 

 traverses these vesicles is especially developed in the outer- 

 most, into which it finds its way in threads down the walls. 

 These threads, at short distances, give off other threads from 

 small nodes into the interiors of these outer vesicles. These 

 latter further become filled with i-efractive matter absorbed 

 from the pigment epithelium, and certainly largely obtained 

 from the pigment granules. This matter absorbed through 

 the walls condenses the mass of the reticulum into the axes 



' Cf. 'Arch, niiiir. Auat.,' Bd. v, 1869, pi. xxii, tig. 2a. See also' Broua's 

 Thierreich ' (Amphibia). 



