158 



LIFE : OUTLINES OF GENERAL BIOLOGY 



poor in nutritive salts, or in water-pools in similar places. Thus 

 sundews (Drosera), buttenvorts (Pinguicula), Venus's Flytrap 

 (Dionica), and the Sarracenia and Ccphalotus pitcher-plants are 

 characteristic of wet moors and swampy places; and most of 

 the Bladderworts (Utricularia) live in moorland pools. Some of 

 the bladderworts are terrestrial, others epiphytic; and most of the 

 pitcher-plants of the Nepenthes type live perched on trees in swampy 

 places. Over four hundred species of Flowering Plants are known to 

 i)e insectivorous; but 250 of these are Utricularias, 100 are sundews, 

 and 40 belong to the genus Nepenthes, so that the remarkable fact 

 is not that so many plants have taken to this jx'culiar mode of 

 nutrition, but that there are relatively so few. In a comer by them- 

 selves may be placed a few carnivorous fungi, such as Arihrobotys 



A Typical I'ltchcr-plant. a species of Xeix^nthes. 1, Stalk of transformed leaf; 

 '2, twist on tendril-like portion; 3, the pitcher itself; 4, the lid; 5, a spur; 

 (k the stem. 



oligospora, living in dung, which catches, kills, and absorbs small 

 threadworms in the nooses of its mycelium, and Zoophagus 

 insidiatts, which does the same for Rotifers. 



l^iTTERWORT.— We begin our survey of these interesting plants 

 with the least striking, the Butterwort, Pinguicula, of which about 

 thirty sjx^cies are known from marshy grounds, especially among 

 the hills, in the Old World and the New. They belong to the same 

 order as the Bladderworts (Lentibulariaceas). A number of plump, 

 glistening yellowish green leaves form a flat ro.sette on the ground, 

 and from the centre a slender upright stalk rises for two or three 

 inches and Ix^ars a beautiful flower, somewhat like a violet in shape 

 and colour. The leaves have a slightly fungus-like smell, possibly 

 attractive to insects, and they are covered with hundreds of minute 

 stalked and sessile glands, which secrete two digestive ferments, one 

 like pepsin and the other like rennet. Linnaeus mentions that the 

 Lapps use the leaves for curdling milk. The secretion entangles small 



