FORTY-NINE GENERATIONS IN THE DARK/ 



FERNANDUS PAYNE. 



Since the time Lamarck put forward the well-known theory 

 of the transmission of acquired characters, this subject has been 

 discussed pro and con by many writers ; some believing that it is 

 one of the guiding principles in the evolution of species; others 

 that the transmission of an acquired character is an utter im- 

 possibility. I shall not attempt a review of the literature, as 

 every book on heredity and evolution has its chapter devoted 

 to that. In fact, it seems to me that there has been too 

 much discussion and not enough experimental work. I believe 

 it can justly be said that there has not been a single decisive 

 experiment which proves or disproves the theory. They are all 

 open to criticism in one way or another. The main argument 

 which the opponents of the theory advance is that there has 

 been no proof brought forward, and further there is no conceiv- 

 able way in which an acquired character could be transmitted. 

 On the other hand, the supporters believe that this is one of the 

 easiest ways of explaining evolution and as it helps us out of 

 many a difficulty it must be true. 



Much interesting data has been collected, but none of it is 

 conclusive. What we need at the present time is more experi- 

 mental work to test the validity of the theory. With this atti- 

 tude toward the subject, I started an experiment October 21, 

 1907, while at Columbia University to test the effect of darkness 

 upon the common fruit fly, Drosophila ampelophora, and, if any 

 effect was noticeable, to test its transmissibility. This seemed 

 to be a suitable experiment as the present condition of cave 

 animals is easiest explained by the assumption of the transmission 

 of acquired characters. 



The paper is not a finished report, but it may be of interest 

 to scientific men to learn that such an experiment is in progress, 

 and that this fly has been bred in the dark for forty-nine genera- 

 tions. Most certainly the length of time is rather short, but the 



' Contribution from the Zoological Laboratory of Indiana University, No. 112. 



