3iG SEA-SIDE STUDIES. 



has considerably disturbed the harmony which existed on 

 the subject of the retina, by the publication of a series of 

 researclies, which led him to the conviction that only the 

 optic fibres of the retina are of nervous structure, the rest 

 being formed of " connective " tissue. "Whatever may be 

 the issue of the quarrel thus raised, it will not affect the 

 points to which our argument will be directed ; indeed, 

 Funke * already suggests that, inasmuch as the function of 

 the rods and cones is one to which nervous tissue is confess- 

 edly incompetent — namely, the transformation of the wave 

 of light into that molecular process which takes place in the 

 conduction of the impression — we may readily admit that 

 their structure is different. 



From what has been already said, it will be easy to prove 

 that no images can be formed on the surface of the retina. 

 In the first place, the retina, during life, is as transparent as 

 glass. The rays of light must therefore pass through it, and 

 enter the pigment layer, which, being perfectly black, ab- 

 sorbs all rays. Further, it has been proved that the optic 

 fibres are totally insensible to light. There is a blind spot 

 in each eye. Would you know the peculiarity of that spot ? 

 It is where the optic nerve enters, and where, consequently, 

 nothing but nerve-fibres exist. There is also a spot in each 

 eye where the sensitiveness to light is at its maximum. 



anatomists having mistaken connective tissue for nervous tissue in so delicate 

 a structure as the retina, what will be thought of the grey matter of the spinal 

 chord being almost entirely formed of connective tissue, with only a very 

 slight admixture of nerve-cells ? Yet this is the conclusion of two independent 

 inquirers, KuI'FEH and Owsiannikow. See Leydiq, Funke, or CanstaTT. 

 * Lckrhuck dcr I'hijsiolo<jie, 711. 



