76 BOTANY. [CHAP. n. 



of glandular hairs, each of which secretes at its swollen 

 tip a sparkling drop of viscid fluid which increases in size 

 as the sun's heat increases, hence the popular name of 

 sundew. If an insect comes in contact with a single 

 gland, more fluid is secreted, and as the victim struggles 

 its movements only hurry on its own destruction, other 

 glands bend over to the place where the struggle is 

 going on, until finally the insect is surrounded by the 

 leaf and eventually digested, after which the leaf slowly 

 expands, the remains of the insect being removed by 

 wind or rain. Nepenthes agrees with the sundew in 

 digesting its prey, the digested matter being then ab- 

 sorbed. In Utricularia and Sarracenia the insects are 

 not digested but become putrescent on the surface of the 

 leaf or in the pitchers, the putrescent matter being then 

 absorbed. In the butterwort, not uncommon in some 

 parts of England, the leaves form a rosette lying on the 

 ground, are of a pale yellow-green colour, and covered 

 on the upper surface with a viscid exudation which acts 

 like birdlime to any insect alighting on its surface. 

 When irritated by the struggles of the insect the leaf 

 curls slowly inwards and enfolds its victim, expanding 

 again when the irritation has ceased and the nitrogenous 

 portions of the insect have been absorbed. The butter- 

 wort digests its food after the fashion of the sundew, 

 but on the whole it does not appear to be specially 

 adapted for the capture of living insects, and depends 

 more on dead nitrogenous matter being deposited on the 

 leaf. The popular name of butterwort is derived from 

 the fact that the leaves were at one time used for the 

 purpose of curdling or giving consistency to milk, due to 

 the presence of the digestive fluid in the leaves. It is 



