402 WILLIAM H. COLE 



of the adult. The outer portion of the wall of the eyeball, the 

 cornea, is not attached to the overlying integument. The latter 

 fits over the eye smoothly, is transparent, and is homologous to 

 the corneal conjunctiva of the adult eye. Figures 19 and 20 of 

 De Waele's paper ('01) illustrate this condition, which is found 

 also in fishes. The conjunctiva consists of an epidermis two or 

 three cells thick and a very thin dermal layer. 



A study of the abnormal conjunctiva revealed the presence 

 in it of xantholeucophores, as well as dermal and epidermal 

 melanophores. The xantholeucophores were fewest and the epi- 

 dermal melanophores were most numerous. The only noticeable 

 feature of their arrangement was the general and even distribu- 

 tion. The animal was isolated and kept under observation for 

 four months, during which time the pigmentation did not change. 

 It was evident that the abnormality had been caused by an in- 

 jury to the conjunctiva. If this was true, it should be possible 

 to duplicate the condition in the laboratory. Five healthy nor- 

 mal animals were selected. Their eyes were carefully examined 

 and were found to show no defects or pathological conditions. 

 No pigment cells of any kind were present in the conjunctivas. 

 By means of a fine-pointed needle the conjunctiva of the right 

 eye of each animal was scratched in many places on the surface, 

 and in two cases was punctured. Twenty-four hours afterward 

 epidermal melanophores were distributed over the conjunctiva 

 in three animals, including both punctured cases, and showed 

 distinct radial arrangement. This arrangement continued into 

 the surrounding skin about 2 mm. back from the edge of the 

 conjunctiva. The other two eyes showed epidermal melano- 

 phores in the outer half of the conjunctiva only, the central re- 

 gion being clear. Radial arrangement was marked. At the 

 close of the second day, they were pigmented over their whole 

 surface, so that all five cases were similar in appearance. By 

 the end of four weeks the number of epidermal melanophores had 

 increased only slightly and dermal melanophores were appearing 

 around the edges of the conjunctiva. All indications of radial 

 arrangement had disappeared. Xantholeucophores first ap- 

 peared during the eighth week after the operation. By this time 



