THE RETINA, BY MAX SC'HULTZE. 



matter, which must consequently assist the selective absorption of the 

 spheroids. 



Moreover another structure adapted to exercise an influence upon 

 the course of the luminous rays, is to be found in the internal segments 

 of the cones in Birds, Reptiles, and Amphibia, and also in the rods 

 of Birds and Amphibia ; namely, a lenticular body of higher refractive 

 power than the substance by which it is surrounded. This occupies 

 the extremity of the inner segment in the rods, and is flattened pos- 

 teriorly towards the outer segments, but anteriorly it presents a 

 spherical or elliptic surface ; in the cones containing spherical oil drops, 

 it is situated immediately in front of and in contact with the drop. W. 

 Krause first observed this body in the cones of the Fowl, and considered 



Fig. 358. 



M 



\ 



t 2 J 4 J 



Fig. 358. 1, 2, 3, Rods of the retina of the Falcon : s', internal seg- 

 ment, with highly refractile lenticular bodies ; s", external segment 

 invested by lineally arranged pigment granules, as they may be seen 

 to adhere to the surface of the outer segments in many specimens 

 hardened in perosmic acid. 4, Rod and cone (z) from the Fowl : fc, 

 yellow flat spheroid in the internal segment of the cone, situated in 

 front of which is an ellipsoidal refractile body. 5, Rod from the 

 Triton : c, plano-concave ; c', biconvex lens in the internal segment. 

 Magnified 800 diameters. 



it must be regarded as the clavate extremity of a nervous central 

 fibre of the internal segment, naming it at the same time the " optic 

 ellipsoid." * I have termed it the lenticular body.f 



* Gottinger Naehrichten, No. 37. 1867. 



t Max Schultze, ArcMvfur Mikroskop. Anatomie, Band iii., p. 221. 



