THE EYE. 747 



haps ^Yith several. The filaments which run inwards from both kinds 

 of " granules," which may be pretty readily traced in vertical sections, 

 are continued in a straight line, or slightly curved, through the layer of 

 gray nerve-substance without any connection with its elements, and 

 enter the expansion of the optic nerve, where, as especially in the pos- 

 terior part of the eye, in which situation the layer of nerve-fibres is 

 thick, it is easy to perceive that they run in the narrow interstices be- 

 tween the nervous bundles, in a fascicular manner towards the memhrana 

 Umitans. I have taken much pains in the investigation of their re- 

 lations at the surface of the retina, and have arrived at the following 

 results. If the inner surface of the retina be examined under a strong 

 magnifying power, in its posterior half, where the fibrous bundles of the 

 optic nerve are still very distinct, a peculiar marking will be observed 

 between them, consisting of series of points, of minute stelliform 

 figures, or of little streaks, which often (also in animals, as the Ox for 

 instance) regularly converge towards each other from the bundles of 

 fibres like the rays of a feather. If these structures are traced in ver- 

 tical sections, it is easily seen that they are nothing but the extremities 

 of the radiating fibres dipping down between the nervous bundles, and 

 presenting a somewhat peculiar aspect. For, whilst in the deeper part 

 of the retina they are simple pale fibres, of at most 0-0008 of a line in 

 size, they are here so modified that some of them simply expand, and 

 terminate in a triangular pale corpuscle, O-0015-O-OOo of a line in 

 length and breadth (Fig. 303' I), from the internal angles of which, one 

 or two horizontal fibres are again given off; whilst the others, without 

 expanding, end in a complete bundle of 5-9 or more fine fibres (Fig. 

 303 ' n), which also turn to the sides and continue in the plane of the 

 nervous expansion. What further becomes of these latter, innermost 

 processes of the radiating fibre-system, I have not yet been fortunate 

 enough to observe, however zealously I have investigated the matter, 

 and regret that the decision of this very important point in the ana- 

 tomy of the retina must still be left in abeyance. The radiating fibres 

 either actually terminate in the filaments observed by me on the surface 

 of the expansion of the optic nerve, or they are continuous with the 

 true fibres of that nerve, or at any rate are in connection with them. In 

 a physiological point of view the latter supposition would, in any case, 

 be the most plausible ; and in support of it, it may be stated, that in 

 the true fibrous bundles of the retina, toijether with the varicose nerve- 

 tubules (Fig. 303^ a, h), there are fibres of another sort (Fig. 303^ c), 

 which, although of equal size, agree in all respects with the radiating 

 fibres in the absence of varicosities, and in their less straight or more 

 serpentine and irregular course. It may be that these fibres are the 

 direct continuations of the horizontal terminal processes of the radia- 

 ting fibres, which subsequently, in their further progress towards the 



