. Biology in America. Biology. The Factors of Evolution 237 availed nothing to increase or decrease tlic size of each "pure line" as Professor -lohannsen called the progeny of his nine- teen seeds, "('an a man add one cubit unto his stature," or a bean one millimeter unto its length? Professor Johannsen thinks Population Diagram Showing the Effi ct of Selection Upon a Mixed Lot of Beans or '' Po(Pulation '' If several thousand beans, selected at random, are sorted ac- cording to size and placed in test tubes, the lower figure will result; those beans of an average siz
. Biology in America. Biology. The Factors of Evolution 237 availed nothing to increase or decrease tlic size of each "pure line" as Professor -lohannsen called the progeny of his nine- teen seeds, "('an a man add one cubit unto his stature," or a bean one millimeter unto its length? Professor Johannsen thinks Population Diagram Showing the Effi ct of Selection Upon a Mixed Lot of Beans or '' Po(Pulation '' If several thousand beans, selected at random, are sorted ac- cording to size and placed in test tubes, the lower figure will result; those beans of an average size will be greatest in number, while the larger and smaller sizes will be fewest. If beans from different test tubes be selected for planting the "pure lines" 1, 2, 3, etc. will result. Further breeding of these "pure lines" will not serve to change the average size of the population^ selection serving merely to sort out the varieties jumbled together in a inLxed "; From Walter, after Johannsen. Similar results have been obtained by several American workers, notably Professor Pearl, who, while at the Maine Agricultural Experiment Station, attempted by selection to increase the laying capacity of hens—and failed; and Pro- fessor Jennings of Johns Hopkins, who has likewise shown that selection is powerless to change the size of the one-celled animal Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Young, R. T. (Robert Thompson), b. 1874. Boston, R. G. Badger
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