126 



FREAKS OF PLANT LIFE. 



them slowly towards the middle of the leaf. Any 

 object, such as a moderately-sized insect, would thus 

 be brought slowly into contact with a far larger 

 number of glands, inducing much more secretion and 

 absorption, than would otherwise have been the case. 

 That this would be highly serviceable to the plant we 

 may infer from the fact that Drosera has acquired 

 highly-developed powers of movement, merely for 

 the sake of bringing all its glands into contact with 

 captured insects. In the case of 

 Pinguicula, as soon as an insect has 

 been pushed for some little dis- 

 tance towards the midrib, imme- 

 diate re-expansion would be 

 beneficial, as the margins 

 could not capture fresh prey 

 until they were unfolded." 1 On 

 the whole, the movements are 

 not accounted for so satisfactorily 

 and completely as in Drosera and 

 Dioncea. 



In all the British butter- 

 worts, and most others, the 

 margins of the leaves naturally curve a little in- 

 wards, and this not only serves to prevent insects 

 being washed away by the rain, but also to retain the 



Fig.1%— LeafofBut- 

 terwort with the edges 

 curved inwards. 



Darwin, " Insectivorous Plants," p. 379. 



