THE DETERMINATION OF DOMINANCE, 307 



results are produced. When the same materials are combined 

 under the conditions of some other complex we may expect, 

 and do find, that there are differences in the behavior and in the 

 products produced. 



That this production of variability in behavior and in the 

 determination of dominance by incident factors is a real and 

 vital process in nature, I have attempted to show by a second 

 series of experiments, in which I placed definite organisms 

 together in a state of nature where they would interbreed freely, 

 in order to see what the resulting products would be. These are 

 the experiments in synthesis. 



Experiments in Synthesis. 



The purpose of these experiments was to determine what the 

 result would be when species which cross freely, and some of 

 whose characters behave Mendelianwise in experiment, were . 

 brought together in a state of nature. It is frequently main- 

 tained, especially by systematists, that crossing in nature, while 

 uncommon, when it does occur is without much effect — a broad 

 statement made a priori, and grounded in the orthodox belief 

 that species for the most part are physiologically isolated one 

 from another. 



An extensive set of these experiments has been in progress 

 for some years, some few of which have now developed far enough 

 to allow of rather definite statements. The method employed 

 has been to take species derived from nature from some restricted 

 locality, to keep close watch upon what goes on in this locality 

 and also to analyze the composition of the species from this 

 locality by cultures in the laboratory. In this way, stocks of 

 known character are obtained from experiment, and also natural 

 stocks whose attributes are well known are developed in the 

 type localities. In the experiments in synthesis either pedigreed 

 stocks from the laboratory, or the stocks from nature, or both, 

 were placed in nature upon their food plant in isolated locali- 

 ties, or in large cages, and allowed to breed as if the introduction 

 were a natural one. 



