140 EDUARD UHLENHUTH. 



by outside writers, all of whom were under the impression that 

 they were contributing something to Roux's theory, but who 

 in reality had hardly grasped more than a few but imperfectly 

 comprehended terms connected with the essential problem. 

 These for the most part misleading publications have caused 

 more error than progress in experimental work. I shall endeavor 

 to prove this point in a subsequent and more extensive article. 



A second disadvantage of Roux's theory is the fact that the 

 extent of the field in which it is applicable becomes more and 

 more restricted with the increasing number of "experimental" 

 investigations bearing directly upon this problem. Conse- 

 quently, in course of time the phenomena which are not in 

 harmony with this principle of functional adaptation increase 

 in number, although they may be explained, together with other 

 phenomena, from another point of view. 



However, by far the weightiest objection to the theory is that 

 it threatens to become more and more of a stumbling block to 

 workers who are setting out to investigate the problems of or- 

 ganic and inorganic life from a common viewpoint. Nowa- 

 days theories such as that of function and functional stimulus 

 can hardly be reconciled with a chemico-physical view of the 

 life processes; for the whole underlying principle of the theory 

 of adaptation does not lend itself to methods of measurement. 

 For this reason a detailed revision of the theory of functional 

 adaptation has become necessary and will be published in a later 

 communication. 



In the present paper I shall report on the results of a few 

 experiments which I began five years ago with the above men- 

 tioned object in view. As they are at the present moment 

 sufficiently advanced to allow of a survey of the whole point 

 at issue and to show that they are qualified to throw some light 

 on the problem of functional adaptation, a preliminary discussion 

 of these experiments may be warranted. 



The experiments in question were performed on the trans- 

 planted eye of Salamandra maculosa. The eye of a larva was 

 transplanted into the neck of another larva, where after a few 

 days' partial or complete disappearance of the retina resulted, 

 ending finally in complete degeneration. The remarkable fact 



