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PINEAL EYE OF YOUNG AND ADULT ANGUIS FRAGILIS. 89 
stand, if one has not the actual specimen at hand. Those 
layers are: firstly, a layer of pigment cells; secondly, a 
nuclear layer; thirdly, a molecular layer; fourthly, a 
second nuclear layer; fifthly, a capsule of connective tissue 
which encloses the whole. De Graaf had figured the 
retina as having a layer of unpigmented cells (“‘ Cyllinder- 
cellenlaag’’) lying internally to the pigmented rods. 
Spencer objects to this statement, and says, that he has 
not found a trace of either of those layers, and he supposes 
that De Graaf has taken the dried up remains of the con- 
tents of the vesicle for cells. I have not found De Graaf’s 
“ Cyllinder-cellenlaag,’ but I do not doubt that what 
De Graaf calls the pigmented rods are merely the pigmented 
cells which I also show in my figure. The pigment forms 
a very dense layer, with only small interruptions, and I 
have not been able to make out whether the pigment lies 
inside cylindrical cells, or whether there are special pigment 
cells which have been pushed between a layer of cells 
corresponding to the rods and cones of the paired eye. 
The lens is pretty flat, its ventral surface being more 
convex than the dorsal one. It is for the greater part 
composed of fusiform cells, only in the centre of its dorsal 
portion we find a few rounded cells. In regard’ to this 
point I shall add a few remarks when treating of the lens 
of the young blindworm. Taken all together, I find the 
pineal eye of the adult Anguis fragilis rather more highly 
developed than I could have expected to find it from 
Spencer’s description and figure. 
THE YOUNG ANG@UIS FRAGILIS. 
The two specimens which I used for examination were 
both about six days old, and about 7°5 cm. in length. 
Of the one I made longitudinal, of the other transverse 
sections. I shall not describe the latter, however, as they 
