This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1908 edition. Excerpt: ... a tremendous effect and which are not constant enough to permit tracing marked hereditary transmission. The changes that have been made in certain cases may be entirely due to mutations and not fluctuations; or they may be due to the comparison of tubers that were physiologically different, such as ...
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This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1908 edition. Excerpt: ... a tremendous effect and which are not constant enough to permit tracing marked hereditary transmission. The changes that have been made in certain cases may be entirely due to mutations and not fluctuations; or they may be due to the comparison of tubers that were physiologically different, such as diseased and healthy, or immature and mature tubers. Proper conclusions can be drawn only after controlled experiments upon an accurately measured character by the use of biometrical methods. 6. HYPOTHESIS OF DEGENERATION Analysis Of The Question Very closely linked with the possible improvement of varieties by the selection of favorable fluctuations, and its equal in economic importance, is the alleged phenomenon of degeneration. The common idea is, that there is a weakening, "a running out" of a variety, so that varieties within a greater or less number of years are certain to become worthless for cultivation. That certain varieties in certain localities do lessen in vigor from year to year is not to be disputed. The question is are there contributing causes, or is it an inner physiological weakening, a protoplasmic degeneration, which must take place owing to long continued bud propagation. The proper analysis of the question is of great importance; for, if such a degeneration must take place through obedience to physiological laws, our good varieties are necessarily doomed to a limited life. A proof that this is true, would make a great difference in the practicability of methods of tuber selection, where the improvement--if granted possible--would at least be slow. Methods of selection to change the composition, involving expensive analyses of mother tubers, as in the case of sugar beets, would be absolutely prohibited unless...
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