Quain's elements of anatomy . d-fibres), which extend from theinner ends of the rods at the membranalimitans externa through the thickness ofthis layer to the outer molecular layer. Theenlargements, of which there is but one toa fibre, situate at any part of its course,are each occupied by an elliptical nucleus,and, in the fresh condition, exhibit a re-markable cross-striped appearance (Henle), the strongly refractingsubstance which mainly composes the enlargement being interruptedby bands or disks of a clearer less refi-acting material, usually two innumber, one on each side of the middle lin
Quain's elements of anatomy . d-fibres), which extend from theinner ends of the rods at the membranalimitans externa through the thickness ofthis layer to the outer molecular layer. Theenlargements, of which there is but one toa fibre, situate at any part of its course,are each occupied by an elliptical nucleus,and, in the fresh condition, exhibit a re-markable cross-striped appearance (Henle), the strongly refractingsubstance which mainly composes the enlargement being interruptedby bands or disks of a clearer less refi-acting material, usually two innumber, one on each side of the middle line (fig. 350), but occa-sionally single and median (see the left-hand one in fig. 350). Therod-fibres are of extreme fineness, and exhibit minute varicositiesin their course: each is directly continuous at the outer endwith one of the rods, but at the inner end appears usually to terminatein a somewhat larger varicosity, fiom which one or more fine fibrils maybe traced extending into the substance of the outer molecular •STEUCTUEE OF THE EETIXA. 415 These are probably connected with the processes of the inner granules,but the connection has not been satisfactorily proved. Fig. 350.—The nervous and epithe- ^^S- 350. LIAL ELEMENTS OF THE RETINA (SEIII- DiAGRAMMATic). After ScLwalbe. The numbers are tlie same as in fig. extent of the molecular layers isindicated merely by linear shading. Those outer granules which areconnected with the cones are, inmost parts of the retina, muchfewer in number than the rod-gTanules, from which they aredistinguished by their shape,which is somewhat pyriform, bythe absence of transverse striation,and by their position—for they (occupy the part of the outer nu-clear layer nearest the membranalimitans externa, and the largerend of each is thus in close proxi-mity to the base of the correspond-ing cone (fig. 349), with which it ^is directly connected, or there is atmost a short, comparatively thickstalk uniting the two (see fig. 35
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