416 H. M. BERNARD. 



retina are obviously bags which have, under pressures and 

 strains, lost their normal cylindrical shapes, and are now 

 pulled out or crushed together into every variety of form, 

 from short, rounded sacs to long, thin clubs with round knobs 

 at the tips.^ Endless, too, are the instances in which the 

 inner and outer limbs have been pulled somewhat apart, and 

 the stretched or torn membrane becomes visible under good 

 microscopic powers. Important, also, in this connection is 

 PI. 30, fig, 1, from a newt, in which in one spot all the rods 

 were broken away, but their basal portions persisted emptied 

 of all contents except the remains of the ellipsoids. This 

 last is a fortunate observation, because it shows that, in 

 essence, the inner and outer limbs are simply two sacs 

 separated by a thin wall, and that the great differences seen 

 between them must be referred entirely to their contents. 

 To this we shall return later. 



Lastly, I have sections of a newt's retina in which the thin 

 coverings of the rods have taken stain, and are quite demon- 

 strable in optical sections. 



External Markings. — The longitudinal striation of the 

 outer limbs of the rods has long been seen, but its nature 

 has never been satisfactorily settled. Max Schultze regarded 

 it as a furrowing of the surface, and figured the cross-sections 

 of the rod as having an outline like that shown in PI. 30, 

 fig. 8. 



With regard to the inner limbs of the rods in Amphibia, 

 exact records of striation are few. The well-known "Faser- 

 korb " of Max Schultze was found by him, '^ essentially the 

 same," in all the classes of Vertebrates, including* the Am- 

 phibia. He records finding it in the axolotl, and he figures 

 it in the newt." Hoffmann also figures the upper ends of 

 these or similar threads round the bases of the inner limbs of 

 amphibian rods, and forming a ring of needle-like points 

 similar to those figured by Max Schultze as projecting from 



1 Max Schultze gives a somewhat siiiuiar figvue, viz. the sac-like rod of a 

 pike, produced artificially ('Arch. mikr. Anat.,' Bd. iii, pi. xiii, fig. 18a). 

 3 ' Arcii. iiiikr. Anat.,' Bd. v, p. 379, pi. xxii, fig. 2a. 



