The Origin Of Floral Structures Through Insect And Other Agencies

Paperback | February 3, 2012

byGeorge Henslow

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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1888. Excerpt: ... CHAPTER XXXII. FERTILISATION AND THE ORIGIN OF SPECIES. The Origin Of Species By Insect Agency.--The attractive features of flowers being now well recognized as correlated with insect agency in fertilisation, the question arises, How have they come into existence? We may suppose that a plant bore seedlings, some of which had, we will say, the corolla accidentally (that means from some unknown cause arising from within) larger on one side than another; and then such a flower, being selected by insects, left offspring which, by gradual improvement through repeated selection, ultimately reached the form it now possesses. As an alternative, we may suppose that the first impulse came from without, and induced by the insect itself; so that the variation once set up in a definite direction, went on improving under the constantly repeated stimulus of insect visitors until the form of the flower was actually conformable to the insect itself. The process of evolutionary development might perhaps be much the same under either supposition, but the latter hypothesis has more than one advantage. First, in the assignment of a direct physical cause for the incipient change, instead of some incidental and unaccountable variation, which must be assumed by the former. Secondly, the theory does not require the plant to make an indefinite number of less useful changes or variations, only to be discarded at each generation for the one form that was wanted. Thirdly, as a great number of flowers would be visited, both on one plant and on many surrounding individuals in the neighbourhood, great numbers might bear offspring advancing more or less in the same direction; and there would be no fear of extermination, even if some happened to be crossed by the parent form. Indeed, the ...

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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1888. Excerpt: ... CHAPTER XXXII. FERTILISATION AND THE ORIGIN OF SPECIES. The Origin Of Species By Insect Agency.--The attractive features of fl...

Format:PaperbackDimensions:102 pages, 9.69 × 7.44 × 0.21 inPublished:February 3, 2012Publisher:General Books LLCLanguage:English

The following ISBNs are associated with this title:

ISBN - 10:021780487X

ISBN - 13:9780217804875

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