Ten New England Blossoms and Their Insect Visitors

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Houghton, Mifflin, 1895 - 142 sayfa
 

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Sayfa 61 - The more I study nature, the more I become impressed with ever - increasing force with the conclusion, that the contrivances and beautiful adaptations slowly acquired through each part occasionally varying in a slight degree but in many ways, with the preservation or natural selection of those variations which are beneficial to the organism under the complex and ever-varying conditions of life, transcend in an incomparable degree the contrivances and adaptations which the most fertile imagination...
Sayfa 97 - ... their petals are rudimentary or quite aborted; their stamens are often reduced in number, with the anthers of very small size, containing few pollen-grains, which have remarkably thin transparent coats, and generally emit their tubes whilst still enclosed within the anthercells ; and, lastly, the pistil is much reduced in size, with the stigma in some cases hardly at all developed.
Sayfa 75 - ... a sharply-pointed common pencil into the nectary. Owing to the pouch-formed rostellum projecting into the gangway of the nectary, it is scarcely possible that any object can be pushed into it without the rostellum being touched. The exterior membrane of the rostellum then ruptures in the proper lines, and the lip or pouch is most easily depressed.
Sayfa 77 - A) it will be evident that the firmly attached pollinium will be simply pushed against or into its old position, namely, into the anther-cell.
Sayfa 75 - ... the anther-cells ; the. discs still form part of the rostellum, but are separate ; and the balls of viscid matter still lie concealed within the rostellum.
Sayfa 77 - ... which causes the pollinium to sweep through an angle of about ninety degrees, always in one direction, viz., towards the apex of the proboscis or pencil, in the course of thirty seconds on an average. The position of the pollinium after the movement is shown at B in fig.

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