Plant-breeding; comments on the experiments of Nilsson and Burbank . do not thrive, nor do they unfold their full statureand quahties as they might under better conchtions. Theygreatly prefer irrigated grounds or the moist air of theforest, and only here display their real nature. Evencacti are originally forest plants, and may be seen stoutlvgrowing between densely thronging shrubs. Thus theconviction is forced upon us, that desert-plants are not,as a rule, the product of aridity. They may have originatedanywhere else, under any other conditions. But throughtheir pecuhar quahty
Plant-breeding; comments on the experiments of Nilsson and Burbank . do not thrive, nor do they unfold their full statureand quahties as they might under better conchtions. Theygreatly prefer irrigated grounds or the moist air of theforest, and only here display their real nature. Evencacti are originally forest plants, and may be seen stoutlvgrowing between densely thronging shrubs. Thus theconviction is forced upon us, that desert-plants are not,as a rule, the product of aridity. They may have originatedanywhere else, under any other conditions. But throughtheir pecuhar quahty of enduring drought, they attainedtheir rapid multiphcation as soon as in their migrationthey reached the arid regions and there found themselvesfree from competition. So it seems to me in all those beautiful cases of fitnessfor pecuhar or extreme influences. \\e do not know howthey have been acquired. We may imagine that usefulnessin the struggle for hfe has preserved some quahties, thebearers of injurious characters being easily stam]^ed out. We ?tI -?^ 3 d. 351 352 PLANT-BREEDING may sketch the development of the spurs of the orchids inconnection with the lengtli of the proboscis of bees andbutterflies, but we cannot directly observe the changes which,we assume, are brought about by such influences. In all thosecases it is equally possible, and in some even probable, thatthey have not been originated in the way in which theplants are now using them. The higher the degree ofdifferentiation, the more probable our mode of explanationmay be, but in the more simple and ordinary cases, includ-ing the desert plants and many similar instances, the environ-ment has only selected the suitable forms from among thethrong, and has no relation whatever to their origin. Present distribution is the effect of migration, andmigration is governed and directed by the given charactersof the species. It produces the intimate relationship of theorganisms to their environment, to climate and soil
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