Chapters in modern botany / by Patrick Geddes.

  • Geddes, Patrick, Sir, 1854-1932.
Date:
1899
Catalogue details

Licence: Public Domain Mark

Credit: Chapters in modern botany / by Patrick Geddes. Source: Wellcome Collection.

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    correspond to those of Sarracenia, which we may therefore describe more minutely. The gaily-coloured lid of the Sarracenia pitcher is bedewed in spring and early summer with drops of nectar, which lie on its inward surface, at least for the most part; not on both, as in the pennon of the Darlingtonia. A closer examination of its surface shows that these drops are at once helped to form, and if sufficiently large to trickle downwards by a coating of fine but short and stiff hairs which arise from the epidermic surface. Here, in fact, is in every way an admirably-constructed attractive surface, and it is obvious as well as natural that the insects which sip the honey should travel down into the interior of the pitcher to seek for more. Beyond the lid surface with its hairs and nectar-glands they come upon the smooth and glassy conducting surface, a well-paved path leading indeed towards destruction. In S. purpurea there are indeed a few fresh nectaries to be reached by this descent, a new secreting surface below the conducting one—in 6. flava and other species not even this,—but in all cases we soon reach the detentive surface of the whole lower part of the pitcher. This is covered with long, stout, bristly hairs, averaging say \ inch long, all sloping downwards into the cavity of the pitchei-, and so presenting no obstacle towards descent, but much resistance towards return, as the finger can easily verify, or as the dead inmates of the tubular prison still more conclusively show. That so comparatively powerful an insect as a wasp or bluebottle can be thus detained may be at first sight perplexing; but we see that there is no scope to use the wings for escape, while legs and wings alike become entangled and held back by the stiffly-pointed hairs, which the struggling insect can at most only thrust along, and thus not break. Another captive soon comes on top;