ILLUSTRATIONS. 



Page. 



Fig. 1. Graphic illustration of the range of fluctuations of each of the eight pure 



races of Paramecium studied by Jennings 28 



2. Graphic illustration of ten generations of corn with no selection, the 



first generation of which is YySs 38 



3. Graphic illustration of the effect of mass selection in cross-fertilized 



species 42 



4. Graphic illustration of ten generations of a hybrid in a self -fertilized 



species without selection to type 50 



5. Graphic illustration of ten generations of a hybrid in a self-fertilized 



species selected for type WWCC 52 



6. Graphic illustration of the effect of individual selection in a self- 



fertilized species on progeny of the hybrid WwCc 53 



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