288 LECTURE XII. 



bacillar layer into the most anterior layers, a series of 

 rows of fine fibres could be traced (radiating fibres, also 

 called Miillerian fibres), which both receive the granules, 

 and support the cones and rods (Fig. 85, B, C). This 

 very complicated apparatus is placed as nearly as possible 

 perpendicularly to the course of the fibres of the optic 

 nerve. The greatest difficulty which exists with regard 

 to the anatomical connection of the parts, is to determine 

 whether the radiating fibres, either by bending directly 

 round, or by a lateral anastomosis, become continuous 

 with the optic or ganglionic fibres, and are thus them- 

 selves nervous, or whether only an intimate apposition 

 takes place, and so the nerves bear no other relation to 

 the radiating fibres than those of proximity. A tactile 

 body may also, you know, be either regarded as a body 

 formed by a swelling of the nerve itself, or as a special 

 structure up to which the nerve only proceeds or into 

 which it enters. This question (of the connections of the 

 radiating fibres) has not yet been definitively settled. At 

 one time the probability became rather stronger that 

 direct communications existed, at another that nothing 

 more than a mere apposition took place. It can, how- 

 ever, even now no longer be doubted, that this appara- 

 tus is essential to the perception of light, and that the 

 optic nerve might exist with all its parts without in any 

 way possessing the power of receiving impressions of 

 light, if it were not connected with this apparatus. It is 

 well known that just that point in the background of the 

 eye, where there are only optic fibres and no such appa- 

 ratus, is the only one which does not receive impressions 

 of light (the blind spot). In order therefore that the 

 light may be rendered at all capable of acting upon the 

 optic nerve, it unquestionably requires to be collected 

 by means of this apparatus of fibres, and it i& therefore 

 an extremely interesting question for delicate physical 



