A PRELIMINAEY REPORT ON SOME GENETIC 

 EXPERIMENTS CONCERNING EVOLUTION 



RICHARD GOLDSCHMIDT 



The nature of the gene, the variability of factors and 

 the effects of selection are favorite topics of recent dis- 

 cussion, which is well known to geneticists. The latest 

 publications of Jennings and Castle will stir up anew the 

 uncompromising parties and lead to new discussions. We 

 think it advisable, therefore, to give a brief account of 

 certain parts of a very large body of work on fundamental 

 questions of evolution which we have carried on during 

 the past nine years, with the collaboration of Dr. Seiler 

 and Dr. Poppelbaum. Although some parts of the work 

 have been finished for some years, we do not intend to 

 publish a full account until all the details are worked out. 

 But as certain results have already allowed us to form 

 definite views in regard to some fundamental questions 

 of evolution, we may present them, together with ex- 

 amples of the experiments in question. 



The majority of the experimental work in regard to 

 the fundamental problems of evolution has been done 

 with domesticated animals and their mutations (rats, 

 Drosophila) or with Protozoa, which present the compli- 

 cation of asexual reproduction. We have directed our 

 attention to experimental analysis of such phenomena in 

 nature, which must give basic information about evolu- 

 tion, and we have studied the following phenomena : 



1. The Geographic Variation of the Gypsy-moth.— This 

 well-defined species is spread over a great part of the 

 globe. In different habitats, however, different races are 

 found. How many of these exist can not be stated, but 

 the number must be extraordinarily large, as we know 

 but two localities where the same race is found. We 

 have found all the races to be perfectly fertile with each 

 other, with the exception of one combination which has 

 never been successful. We have studied and are still 

 studying the genetics of a large number of these races. 

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