. Heredity and evolution in plants . in North America. 123. Evidence from the Distribution of geographical distribution of the lower cryptogams(below the ferns and their allies) has not been the subjectof as extensive study as that of the ferns and floweringplants, but the evidence marshalled by Campbell1 in 1907,concerning the distribution of the liverworts (Hepaticai),illustrates in a striking manner the importance of the. FIG. 783.—Seed capsule and seeds of an orchid. facts of geographical distribution in endeavoring todetermine the question of the relative age of a group of
. Heredity and evolution in plants . in North America. 123. Evidence from the Distribution of geographical distribution of the lower cryptogams(below the ferns and their allies) has not been the subjectof as extensive study as that of the ferns and floweringplants, but the evidence marshalled by Campbell1 in 1907,concerning the distribution of the liverworts (Hepaticai),illustrates in a striking manner the importance of the. FIG. 783.—Seed capsule and seeds of an orchid. facts of geographical distribution in endeavoring todetermine the question of the relative age of a group ofplants. It had been argued by Scott, in 1906, that theliverworts were probably of comparatively recent originbecause of the almost entire absence of fossil remains in thePaleozoic rocks. But, as Scott himself records, impres-sions have been described from Paleozoic strata of plantforms that can be assigned only to the Hepaticae, andindeed to one of the most highly organized groups—the 1 Campbell, Douglas Houghton. On the disl ribution of the Heptaticae,and its significance. NewPhytologist 6 : Oct. 1907. GEOGRAPHICAL DISTRIBUTION 173 Marchantiaceae. This, of course, means a long periodof evolutionary development from similar forms to themore complex, preceding the geological age of the rockscontaining the fossil record, and one such bit of positiveevidence fully substantiated, is of itself sufficient toestablish the anti
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