﻿Eye of stygicola. 221 



In these young the eyes are in contact with the skin and iill a large part of the 

 fibrous orbit. With age the eyes come to be farther and farther removed from the 

 skin, and lie in the orbital fat, which may be many times the size of the eye. For 

 instance, in the mother of the young (125 a and b) the eyes are appro.ximately in the 

 middle of the large eye cavity, which is over a thousand times as large as the eye, 

 having on the left side avertical diameter of 1.8 mm. and a lateral diameter of 3 mm., 

 whereas the eye has an average diameter of but 0.2 mm. The eyes are about 0.13 

 mm. removed from the surface. The eye cavity is filled with cavernous connective 

 tissue meshwork holding fat. About the eye the meshes are stronger and very 

 rich in blood-vessels. About the eye in this individual, as in all old ones, there are 

 also large accumulations of pigment. 



Parts of the eye have certainly begun to degenerate before birth. The lens 

 leads in this respect. After birth there is a rapid general degeneration of the eye. 

 This is not directly proportional to the increase in size of the fish. For instance 

 (see table), in a specimen 60 mm. long the eyes are distinctly farther reduced than 

 in one of 88 mm. The left eye (plate 25, fig. g) in life was surrounded by stagnant 

 blood. The choroidal blood-vessels were distended and the vessels of the vitreous 

 body were also abnormally large. The entire eye was compact, and the retina, 

 slightly withdrawn from pigment layer by reagents, shows a drawn-out process indi- 

 cating an intimate relation between two layers. Figure f (right eye) shows eye nor- 

 mal to this stage. The retina has shrunken away from the pigment layer somewhat 

 and an artificial space has also been formed in places between sclera and choroid. 



As in Lucifuga, the eyes of opposite sides have at times undergone dift'erent 

 modifications ; the eye on one side may be contracted into a compact ball, while on 

 the other it is distended into a hollow sphere, eight or ten times as great in cubic con- 

 tents. The left eye of 125 a and the left of 126 (plate 25, fig. G, and plate 26, fig. a) 

 indicate that in these two eyes at least, the compression is associated with an accu- 

 mulation of blood in the choroid vessels and in the orbital fat. While this blood 

 does not have the appearance of a clot, the corpuscles have a very dift'erent staining 

 reaction from those in the vessels. In 126 I there is a small vessel in front of the 

 iris which contains normal blood (plate 26, fig. A, cps.), otherwise this eye is shut 

 off from the circulation. The left eye of 125 a was certainly cut off from the 

 circulation by the formation of a large blood lake about the eye. There is evi- 

 dence in the right eye of 125 that extra limital blood has accumulated about this 

 eye also. It would seem from these examples that one of the principal causes of 

 degeneration is a disturbance in the circulation. 



Figure A of plate 26 shows the left eye of No. 126, 88 mm. long. The choroid 

 blood-vessels are distended with blood corpuscles which stain differently from 

 those in one of the choroid vessels. Other spaces or vessels filled with blood were 

 found in tracts passing through the orbital fat-mass, past the eye. The iris was 

 infolded and the pupil closed with a fibrous tissue containing blood-vessels. The 

 lens was a flaccid membranous bag containing pigment granules and a few nuclear 

 remains. The pigment layer variously pigmented (i) appears in two layers in 

 places, and within it are found large rounded masses of pigment. The retina con- 

 sists of ganglionic cells, and an outer layer of cells and a reticular layer, approxi- 

 mately divided in the middle by an irregular cellular layer. The optic nerve in 

 the figure is supplied from neighboring sections. 



