T.J INSECTIVOROUS PLANTS. 5 



by a drop of an exceedingly viscid solution, which, 

 glittering in the sun, has given rise to the name of the 

 plant If any object be placed on the leaf, these 

 glandular hairs slowly fold over it, though if it be inor- 

 ganic they soon unfold again. On the other hand, if 

 any small insect alights on the leaf it becomes en- 

 tangled in the glutinous secretion, the glands close 

 over it, their secretion is increased, and they literally 

 digest their prey. Mr. Frank Darwin has recently 

 shown that plants supplied with insects grow more 

 vigorously than those not so fed. It is very curious 

 that while the glands are so sensitive that even an 

 object weighing only -rgTrcr of a grain placed on them 

 is sufficient to cause motion, yet they are " insensible 

 to the weight and repeated blows of drops " of even 

 heavy rain. 



Drosera, however, is not our only English insect- 

 ivorous plant. In the genus Pinguicula, which fre- 

 quents moist places, the leaves are concave with 

 incurved margins, and the upper surfaces are covered 

 with two sets of glandular hairs. In this case the 

 naturally incurved edges curve over still more if a 

 fly or other insect be placed on the leaf. 



Another case is that of Utricularia, an aquatic 

 species, which bears a number of utricles or sacs, 

 which have been supposed to act as floats. Branches, 

 however, which bear no bladder float just as well as 

 the others, and there seems no doubt that their real 

 use is to capture small aquatic animals, which they do 

 in considerable numbers. The bladders in fact act on 

 the principle of an eel-trap, having an orifice closed 

 with a flap which permits an easy entrance, but 



