Border areas

Usage examples of margins.

In Aldrovanda it appears to be the basal parts alone which contract and carry with them the broad, thin margins of the lobes.

Hooker, and were seen by me in the margins of the leaves of Pinguicula.

This was likewise the case with the short tentacles round the margins of the disc, which had not as yet become inflected.

But it is a curious fact that some of the closely adjoining tentacles on the same leaf, both on the disc and round the margins, were much, and some, apparently, not in the least affected.

The whole convex surface, down to the roots-for there is no distinct footstalk-is covered with short glandbearing tentacles, those on the margins being the longest and reflexed.

The upper surface of the leaf is thickly covered, excepting towards the margins, with minute glands of a reddish or purplish colour, the rest of the leaf being green.

As this takes place, the margins gradually become a little everted, so that the spikes, which at first intercrossed, at last project in two parallel rows.

Some of the points on the infolded margins likewise contained brownish granular matter.

The points on the infolded margins are like those in the Australian form.

I scratched the margins of two leaves for some minutes with a blunt needle, but no effect was produced.

We learn from the foregoing experiments that the margins of the leaves curl inwards when excited by the mere pressure of objects not yielding any soluble matter, by objects yielding such matter, and by some fluidsnamely an infusion of raw meat and a week solution of carbonate of ammonia.

It is only the margins of the leaf which bend, for the apex never curves towards the base.

We can thus, also, understand how it is that so many insects, and fragments of insects, are generally found lying within the incurved margins of the leaves.

In the case of Pinguicula, as soon as an insect has been pushed for some little distance towards the midrib, immediate reexpansion would be beneficial, as the margins could not capture fresh prey until they were unfolded.

It has already been remarked that plants growing in a state of nature have the margins of their leaves much more strongly incurved than those grown in pots and prevented from catching many insects.