52 H. M. BERNARD. 



early stage with (a) small cones, (b) " Scliwalbe's rods/' 

 and (c) fully formed rods, into a stage with only two kinds 

 of elements, viz. (a) rods with enormonsly swollen inner 

 limbs, and (b) '' Schwalbe's rods " with long thread-like 

 inner limbs, fully justifies the appeal which throughout all 

 these papers we have made to pressure in order to account 

 for the form-phases of the elements of the bacillary layer. 



(4) The fact that in the eyes of all Vertebrates higher than 

 fish refractive matter no longer accumulates in the inner 

 limbs, at least so as to swell them to such disproportionate 

 sizes, apparently justifies the conclusion that these accumula- 

 tions are not helpful to the specific function of the retina. 



Returning to the subject in hand, we must now show how 

 the refractive matter ultimately escapes from these swollen 

 inner limbs of fish retinas. 



Reference to the sections of the cod leaves no doubt on 

 this point; the very size of the ''giant cones," and the 

 coarseness of their connections, reveal what the smaller 

 elements of other eyes could not so plainly show, at least 

 until the facts have already been made clear. What I take 

 to be a thick stream ascends from each of these " giant 

 cones," and ends in a refractive clump against the outer 

 reticular layer, the " cone " nuclei being sometimes elongated 

 in the line of the stream. The terminal clumps form, as it 

 were, conical expansions where the streams meet the tan- 

 gentially arranged tissue of the outer reticular layer. Here, 

 again, microscopic examination of the "stream," and espe- 

 cially of its large conical expansion, as seen in the cod, show 

 at once the presence of the same matter as that in the inner 

 limbs. It is not meant, of course, that this matter is alone 

 present, for in what follows it will be seen that this refractive 

 matter follows the threads and fibres of the cytoplasmic 

 network of the retina. In this case the stream and its 

 conical expansion doubtless have a cytoplasmic framework. 

 These streams with their expansions occur in one form or 

 another in most if not all eyes, at least as physiological 

 stages, and are usually described as the "cone fibres " with 



