Alt — Histology of the Eye of Typhlotriton Spelaeus. 87 



2.) The next two in size had eyelids and a small pal- 

 pebral fissure, the upper eyelid, however, overlapped the 

 lower one. (See Figs. 3, 6 and 11.) In the two largest 

 specimens I could not find the smallest palpebral open- 

 ing. It seems that no light whatever could enter their 

 eyes except after having passed through the semi-trans- 

 parent lids covering them. (See Figs. 5, 8 and 12.) 



Unfortunately the preservation of the material for 

 examination was not such as we are accustomed to with 

 the material taken from man. One specimen was still 

 alive when I got it. Yet, even in this animal's eyes, into 

 which the preserving and hardening fluids evidently did 

 not enter in a sufficient quantity, certain post mortem 

 changes took place. Another difficulty lay in the fact 

 that the celloidin in which I embedded the decalcified 

 heads for cutting did not penetrate into the interior of the 

 eyes in such a way as to fill the cavities and give the 

 whole a uniform firmness. In consequence the eyes were 

 more or less shrunken and the tissues did not always lie 

 in their natural positions and relations to each other. 

 Some parts, like the uveal tract, were always more or 

 less disintegrated. In quite a number of sections the 

 crystalline lens fell out during the handling and stain- 

 ing. I cut some of the heads vertically to the surface 

 and some parallel to the surface, hoping to get in this 

 way a more complete picture of the real conditions. 



In the two specimens which had as yet no eyelids 

 (Figs. 1 and 2) the outer skin seems simply to pass over 

 the eyes. But it shows decided structural changes in 

 this ocular part, so as to be easily recognized as the 

 cornea. While the epithelium of the skin in the neigh- 

 borhood of the eye consists chiefly of cylindrical and 

 goblet-shaped cells, it is suddenly changed into a strati- 

 fied epithelium where it covers the eye. While in the 

 four eyes without lids I can find no section in which 

 the whole of this corneal epithelium is intact, on account 

 of the lack of protection, yet larger portions, and espe- 

 cially the peripheral parts, were in a larger number of 



