391 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



restricted to a few localities in North and South Carolina, mainly 

 around Wilmington. Cephalotus occurs only near Albany in 

 Western Australia, Heliamphora on the Roraima Mountains in 

 Venezuela, and Darlingtonia on the Sierra Nevada of California. 

 The six or eight known species of Sarracenia are scattered over 

 the Eastern States of North America. The forty species of 

 Nepenthes are mostly natives of the hotter parts of the Indian 

 Archipelago, but a few range into Ceylon, Bengal, Cochin China, 

 and some even into Tropical Australia, on the one hand, and into 

 the Seychelles and Madagascar on the other. Pinguicula is 

 abundant in the North Temperate zone, and ranges down the 

 Andes as far as Patagonia. The 150 species of Utricularia are 

 mostly aquatic, and found in all save the Polar regions. Their 

 unimportant congeners, Genlisea and Polypompholix, occur in 

 Tropical America and in Western Australia respectively. It is 

 remarkable that all insectivorous plants agree in inhabiting damp 

 heaths, bogs, marshes, and similar situations where water is 

 abundant — a peculiarity perhaps due to their habit of copious 

 secretion, and consequent need of water. Although our know- 

 ledge of insectivorous plants dates from 1768, when Ellis sent to 

 Linnaeus a remarkable letter giving a description of the " Fly- 

 trap " and its habits, it was not till 1860, when Charles Darwin 

 began the thorough experimental study of insectivorous plants, 

 comparing their sensitiveness, mobility, and digestive powers 

 with those of animals, culminating in his classical work, that 

 their physiological import was rightly understood. Since then 

 the investigation of these plants has been kept steadily in view, 

 the analysis of their vital processes becoming with each year 

 more complete. 



Beginning with DroseracecB, and choosing the common Dro- 

 sera rohuidifolia, we find that the leaves are beset with 

 numerous hair-like structures with glandular knobs, to which 

 Darwin has applied the term "tentacles." Each tentacle con- 

 sists of a stalk, at the extremity of which is a glandular knob 

 surrounded by an extremely viscid fluid secretion, which, from its 

 glittering in the sun, has given the plant the name of " Sundew." 

 When a fly alights on a leaf it is immediately entangled amongst 

 the glands ; these, on becoming excited, transmit a motor impulse 

 to all the surrounding tentacles, which immediately bend over 

 and soon kill it. The time during which the tentacles remain 



