. Handbuch der Blume Bestäubung: auf Hermann Mu?ller Arbeit" die Befruchtung der Blüten durch Insekten". Düngung von Pflanzen. Fliegen Blumen 133 Die weiße Blüten, an deren Eingang mit zwei gelben sacs {a) mit gelben Haaren bedeckt verziert, in erster Linie an mittelgroße Fliegen, die Kriechen in den körperlichen bis ihre Köpfe Projekt in die hohle Sporn {c). Dieses ist frei von Nektar, sondern auf die innere Oberfläche der unteren Seite gibt es kleine einzellige capitate Haare, und die Zelte der saftigen Staats erscheinen diese als Nahrung für den dipterous Besucher zu dienen. Die steife Haare gerichtet

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. Handbook of flower pollination : based upon Hermann Mu?ller's work 'The fertilisation of flowers by insects' . Fertilization of plants. FLY FLOWERS 133 The white flowers, ornamented at their entrance with two yellow sacs {a) covered with yellow hairs, chiefly attract medium-sized flies, which creep in bodily till their heads project into the hollow spur {c). This is devoid of nectar, but on the inner surface of its lower side there are small unicellular capitate hairs, and the con- tents of the juicy heads of these appear to serve as food for the dipterous visitors. The stiff hairs directed obliquely backwards, that occur at the entrance to the spur (at b), permit the flies to thrust in their heads with ease, and further serve them as a convenient resting-place, but also prevent the head from being rapidly withdrawn. This can only be gradually eff'ected by the fly pressing its body upwards as far as possible from among the blockading hairs that grasp it. In doing this it touches the anthers with its back, folding forwards and upwards the stigmatic lobe that covers them. The flowers being protogynous, the fly regularly effects cross-pollination, . Fig. 48. Pinguicula alpina^ Z-., a Fly Pinch-trap Flower (after Herm. Miiller). X. Flower seen from the side. XI. The same in longitudinal section (x 3J). XII. Sexual parts of the same (x 7). XIII. Upper half of flower with anthers still closed (x i^J). XIV. Sexual parts of the same (x 7). XV. Sexual parts of a flower, of which the anthers have dehisced. The lower stigmatic lobe is folded upwards from behind, so that its under-surface is visible. XVI, Lower half of the flower. XVII. Two of the capitate hairs, with which the inner wall of the spur is clothed {x Ko). applying the pollen of the older flowers to the stigmas of the younger ones. Such flies as are large enough to be gripped, but too feeble or clumsy to withdraw in the proper way, remain sticking and perish by starvation. Pinguicula alpina is therefore, as Herman

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• bookcentury1900
• bookdecade1900
• bookpublisheroxfor
• bookyear1906