INCEPTION OF INSECT METAMORPHOSIS, 337 



younger specimens, and an acceleration in the contrary case i.e., 

 the transplanted as well as the own eyes of the foster-mother under- 

 went metamorphosis at the same time. But the disagreement of 

 these results with the behavior of the transplanted insect organs in 

 my investigations is only apparent. The influence of the sur- 

 roundings on the grafted eye, observed by Uhlenhuth, was to be 

 remarked only when the age of the specimens on which the eyes 

 were implanted did not differ much from that of animals whose 

 eyes were taken for the operation. In the remaining cases i.e., 

 under the conditions which alone corresponded to my investigations 

 on the transplantation of organs from young caterpillars after their 

 third or fourth moult to full-grown caterpillars or chrysalids and 

 vice versa the grafted eyes retained their proper developmental 

 rate without being influenced by the new surroundings, just like 

 the organs of insects transplanted in my experiments. Nor do my 

 experiments on insects in any way contradict the experiments of 

 Weigl ('13) which were made simultaneously with but independ- 

 ently of those of Uhlenhuth. Weigl studied the same problem in 

 his investigations on the homo- and heteroplastic transplantation of 

 the skin in salamanders and other amphibians. In regard to the 

 course of the metamorphosis of the grafted pieces of skin, he comes 

 to the same general conclusion as Uhlenhuth. In the experiments 

 of Kornfeld ('14) we can also find a parallel to the results I 

 observed on insects. This author, who transplanted the gill of 

 salamanders, agrees in his final conclusion with Uhlenhuth. Uhlen- 

 huth ('13), mentioning my former experiments on the transplanta- 

 tion of gonads in moths, imputes to me results completely different 

 from those which I really obtained (Kopec, 'n). More recently 

 this error has been corrected by Kornfeld in agreement with 

 Uhlenhuth. 



In specimens deprived of the brain or of other nervous ganglia 

 we often may observe certain mechanical difficulties during pupa- 

 tion and emergence of the moth. They are produced by con- 

 crescence of the chitin at the place of operation, and cause the 

 appearance of certain deformities of chrysalids or of moths. It 



* 



must -be distinctly noted that all these deformities, caused only by 

 mechanical obstructions during pupation or emergence of the 

 moths, are in no wise dependent on the operation itself, nor conse- 



