140 PLANTS WHICH EXHIBIT MOVEMENTS IN THE CAPTURE OF PREY. 



a similar mechanism. Here the glands occur on the under surface of the aerial leaves, 

 the cushion glands being by far the most numerous. Shoots of this plant if in- 

 jected with water at the cut end, readily pass it out by their leaves, and in particu- 

 lar by those portions which abound in cushion glands. As the water percolates 

 through these areas it gushes from the leaves with great rapidity. The younger 

 leaves drip with moisture and water drops from the leaf -tips and wells up in the 

 leaf -axils, running in cascades down the stem. 



Somewhat similar is the Yellow-Rattle (Rhinanthus Christa-galli). Here, too, 

 under pressure, water is forced from the leaves, but less rapidly than in the last 

 instance. It is thus possible to observe its excretion from the edges of the under 

 surfaces of the leaves, to see the water drawn round by capillarity on to the upper 

 surface, whence it runs down the vein furrows, as in irrigation canals, to the base 

 of the leaf. 



In these and other cases like them we are dealing with plants which live in 

 moist or even marshy situations. When this is understood, it is not surprising that 

 they should exhibit supplementary mechanisms for eliminating their excess of water. 



CAENIVOEOUS PLANTS WHICH EXHIBIT MOVEMENTS IN THE CAPTUKE 



OF PREY. 



We have taken Nepenthes, Sarracenia, and other forms as types of that section 

 of carnivorous plants which manifest no external visible movement in the pitfalls 

 for the purpose of capture or digestion. The second section, now to be discussed, 

 includes plants in which movements of the leaves, or parts of leaves, modified as 

 organs of seizure and digestion, take place as a result of the contact of animal 

 bodies movements which have the common object of bringing about the digestion 

 of the animals, whilst the retention of the latter is effected in very various ways. 



Whilst in the forms hitherto considered the mechanism of capture is wholly 

 passive, the plant with its pitfall attractively coloured or cunningly baited with 

 honey merely awaiting the moment when the insect slips on the treacherous 

 surface, in those which we are now about to review, a series of movements simple 

 or complex is set up by the stimulus received when the insect alights. In some 

 cases the whole leaf suddenly changes its form, going off like a rat-trap, in others 

 it is merely the digestive tentacles which change their position. In general, when 

 the movement is slow the organ is sticky, but when instantaneous, adhesiveness 

 is not met with. 



The first group of carnivorous plants which perform movements for the capture 

 of prey is composed of the various species of the genus Pinguicula (Butterwort). 

 Of this stock nearly forty species are known; and they are all much alike. Scarcely 

 any difference would be detected by an ordinary person between Pinguicula 

 calyptrata from the mountains of New Granada and Pinguicula vulgaris from 

 our own hills. In respect of habitat, too, they exhibit close conformity. In both 

 the Old World and the New they only thrive on damp spots, the neighbourhood of 



