142 EDUARD UHLENHUTH. 



of the eye in the case of several Proteus which were kept in the 

 light, directly to the influence of function, and Roux is apparently 

 of the same opinion. This point will be discussed by the writer 

 in a later paper. 



My own observations on the transplanted eye of Salamandra 

 soon convinced me that this case lends itself very well for the 

 test of the theory of functional adaptation. 



First of all I severed the optic nerve, a procedure which ac- 

 cording to general opinion should induce permanent degeneration 

 of the retina as a result of the eye becoming isolated from the 

 brain. In all previous operations of this nature, where, however, 

 the eye remained in its normal position, a reunion of the ampu- 

 tated stumps of the nerve took place, so that it was natural to 

 suppose that the re-connection of the eye with the brain brought 

 about regeneration of the retina. In my own experiments I 

 obviated the possibility of such subsequent reunion of the eye 

 with the brain by transplanting the eye to an abnormal position 

 (in the neck of the salamander). But regeneration took place 

 in spite of this fact. The point of chief interest, however, is 

 the fact that by means of this operative measure, which, as 

 has been demonstrated in 95 per cent, of the cases, excludes 

 reunion of the eye with the central nervous system, the eye is 

 permanently deprived of functional power. 



It is thus obvious that in these eyes no function was pos- 

 sible and the experiment therefore shows that a whole series 

 of phenomena, hitherto designated as cases of functional adapta- 

 tion, require a different explanation. We will now discuss these 

 phenomena in greater detail. 



I. In about a week after transplantation of the eye into the 

 neck of the salamander the retina had degenerated to such an 

 extent that in many cases only the peripheral part of the retina, 

 which was not differentiated in layers, had survived. 1 But 

 in spite of its permanent isolation from the brain and despite 

 the fact that the eye was permanently deprived of function, 

 the retina from this time on began to show signs of regeneration 

 and the transplanted eye began to receive a progressively im- 



1 E. Uhlenhuth, "Die Transplantation des Amphibienauges," Arch. f. Ent- 

 ivcklungsm., 1912, XXXIII. 



