Dedication papers : scientific papers presented at the dedication of the laboratory building and plant houses, April 19-21, 1917

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If there are possibilities for hybridization, the pollen ist less uniform 1. Zannichellia palustris (monotypic) 2. Potamogeton (many species) 3. Rubus odoratus (flowering later than other Rubus) 4. Rubus villosus (many species of Rubus flowering the same time) 5. Ranunculus rhomboides (flowering earlier than other Ranunculus) 6. Ranunculus acrís (many species of Ranunculus flowering the same time)
Identifier: dedicationpapers00broo (find matches)
Title: Dedication papers : scientific papers presented at the dedication of the laboratory building and plant houses, April 19-21, 1917
Year: 1918 (1910s)
Authors: Brooklyn Botanic Garden
Subjects: Plants
Publisher: Brooklyn, N.Y. : Brooklyn Botanic Garden
Contributing Library: The LuEsther T Mertz Library, the New York Botanical Garden
Digitizing Sponsor: The LuEsther T Mertz Library, the New York Botanical Garden

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ata derived from genetical behavior, in speculations in regardto the origin of species. It seems clear from the evidence supplied on the systematic andphytogeographical sides on the one hand and that from the standpointof morphology on the other, that the crossing of species in nature isan extremely common cause of the multiplication of species. It isfurther obvious that physiological and genetical criteria must not begiven greater weight than the more reliable ones supplied by actualhistory and by morphological structure, in the all-important biologicalquestion of the origin of the species. It is finally apparent that thegenetical status of the Oenotheras is so dubious that they cannot bebrought into court to furnish decisive evidence in favor of the muta-tion hypothesis of De Vries. It may be added in conclusion that themultiplication of species by hybridization does not by any meansinvalidate the Darwinian hypothesis but merely supplies an additional Brooklyn Botanic Garden Memoirs
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Jeffrey: Evolution by Hybridization JEFFREY: EVOLUTION BY HYBRIDIZATION 305 agency for the formation of species. It appears moreover logicallyimpossible to regard hybridization as the universal and sole cause ofthe appearance of new species, as has been recently maintained byLotsy in his Evolution by Means of Hybridization, since the originalspecies must have come into existence by some other means than byhybridization. The adaptation of the floral structures of the Angio-sperms to cross fertilization, emphasized many years ago by theAustrian botanist Kerner is doubtless of significance in connectionwith the ever-increasing volume of evidence for the wide occurrenceof natural hybrids in this large and successful group of seed-plantswhich have to so notable a degree furnished the facts for the existinggeneral biological theories. DESCRIPTION OF PLATE V Fig. I. Pollen of Zannichelka palustrts, showing great uniformity in a speciesunable to hybridize. X 400. Fig. 2. Pollen of Potamogeton

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