Darwiniana; Essays and Reviews Pertaining to Darwinism eBook

This eBook from the Gutenberg Project consists of approximately 379 pages of information about Darwiniana; Essays and Reviews Pertaining to Darwinism.

Darwiniana; Essays and Reviews Pertaining to Darwinism eBook

This eBook from the Gutenberg Project consists of approximately 379 pages of information about Darwiniana; Essays and Reviews Pertaining to Darwinism.
the upper face of which especially is beset and the margin fringed with stout bristles (or what seem to be such, although the structure is more complex), tipped by a secreting gland, which produces, while in vigorous state, a globule of clear liquid like a drop of dew—­ whence the name, both Greek and English.  One expects these seeming dew-drops to be dissipated by the morning sun; but they remain unaffected.  A touch shows that the glistening drops are glutinous and extremely tenacious, as flies learn to their cost on alighting, perhaps to sip the tempting liquid, which acts first as a decoy and then like birdlime.  A small fly is held so fast, and in its struggles comes in contact with so many of these glutinous globules, that it seldom escapes.

The result is much the same to the insect, whether captured in the trap of Dionaea or stuck fast to the limed bristles of Drosera.  As there are various plants upon whose glandular hairs or glutinous surfaces small insects are habitually caught and perish, it might be pure coincidence that the most effectual arrangement of the kind happens to occur in the nearest relatives of Dionaea.  Roth, a keen German botanist of the eighteenth century, was the first to detect, or at least to record, some evidence of intention in Drosera, and to compare its action with that of Dionaea, which, through Ellis’s account, had shortly before been made known in Europe.  He noticed the telling fact that not only the bristles which the unfortunate insect had come in contact with, but also the surrounding rows, before widely spreading, curved inward one by one, although they had not been touched, so as within a few hours to press their glutinous tips likewise against the body of the captive insect—­thus doubling or quadrupling the bonds of the victim and (as we may now suspect) the surfaces through which some part of the animal substance may be imbibed.  For Roth surmised that both these plants were, in their way, predaceous.  He even observed that the disk of the Drosera-leaf itself often became concave and enveloped the prey.  These facts, although mentioned now and then in some succeeding works, were generally forgotten, except that of the adhesion of small insects to the leaves of sundews, which must have been observed in every generation.  Up to and even within a few years past, if any reference was made to these asserted movements (as by such eminent physiologists as Meyen and Treviranus) it was to discredit them.  Not because they are difficult to verify, but because, being naturally thought improbable, it was easier to deny or ignore them.  So completely had the knowledge of almost a century ago died out in later years that, when the subject was taken up anew in our days by Mr. Darwin, he had, as we remember, to advertise for it, by sending a “note and query” to the magazines, asking where any account of the fly-catching of the leaves of sundew was recorded.

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Darwiniana; Essays and Reviews Pertaining to Darwinism from Project Gutenberg. Public domain.