Ill 



OtJier Iitsectivorous Plants 41 



with stalked glands which secrete a viscid dewdrop- 

 like juice. On these leaves insects, attracted it may be by 

 the glistening drops and by the reddish colour, but more 

 probably by the honey-like fragrance, alight, and knocking 

 off drops from the stalked glands become besmeared and 

 choked. They sink on the surface of the leaf and then 

 small unstalked, uncoloured glands exude a dissolvent 

 secretion. On a plant a year old, which had lived in a 

 glass house with open doors, Goebel on one occasion 

 counted no less than 233 distinctly visible flies, distributed 

 over nineteen leaves. 



Belonging to the same order as Drosophyllum and 

 the more familiar Drosera, there are two other sticky 

 plants in which the "insectivorous habit" is not more than 

 incipient. These are Roridula dentata from the Cape, 

 and Byblis giga7itea^ the latter with simple glands, scarce 

 differing appreciably from those on many other kinds of 

 plants, though with a more copious and glutinous juice. 

 They are interesting in showing the beginnings of the 

 peculiarity which becomes so marked in the sundews, and 

 in the same connection we should notice that leaves and 

 stems of some geraniums, sedums, and primulas have glan- 

 dular surfaces on which insects become entangled. 



Butterworts. — The Common Butterwort {Pinguicula vul- 

 garis) is very common on marshy grounds, especially among 

 the hills. It has a wide geographical distribution, repre- 

 sents a genus with about forty species, and belongs to the 

 same order as Utricularia {LentibulariacecB). It has long 

 been known, though not in connection with insect-catching, 

 for Linn^us noted that the Lapps used it for curdling 

 milk. Every one who has tramped over high wet moor- 

 lands or followed the banks of a mountain stream up into the 

 hills know the appearance of the plant, — the rosette of plump 

 ghstening leaves prostrate on the ground, the beautiful 



