DEOSEKA AND SAEEACENIA. 



383 



Kg. 661. 



and it would appear that albuminous food is thus taken up by the 

 plant for its nourishment. 



The species of Drosera are widely distributed; 

 three species and some varieties being found in 

 Britain, and numerous species occurring in Australia 

 {fig. 88, p. 32), Equatorial America, and South 

 Africa. Experiments have been made upon the 

 British species, as well as upon Drosera Whittakeri 

 •of Australia, D. filiformis of Forth America, and 

 on some African species. In all these, leaf move- 

 ments, of the nature described, have been observed 

 in a greater or less degree. 



The species of the genus Pinguioula appear also 

 to secrete a viscid fluid, which detains insects. The 

 leaves curl in at the margin, but the presence of 

 irritability is doubtful. 



We may here make some remarks on plants which seem also to be 

 insectivorous, although not displaying excitability and contractility. 

 We may specially notice the species of Sarracenia (Trumpet-leaf). The 

 leaves of these plants are all radical, with a more or less tubular petiole, 

 the blade being small, and often lying over the orifice of the tube (fig. 

 203, p. 96). In some of the tubular petioles honey-like matter is secreted, 

 and this attracts insects, and a secretion collects at the bottom of the 

 tube, which seems to have the power of destroying them. In the 

 case of Sarracenia variolaris (Spotted trumpet-leaf) the inner surface 

 of the tube or pitcher, from the mouth to midway down, is smooth 

 iind velvety to the touch, as the finger is passed downwards ; from 

 midway there are retrorse bristles, increasing in size downwards, and 

 ceasing near the base. Insects are attracted by a viscid, honey-like 

 substance, secreted from the internal surface of the pitcher, and ex- 

 tending a short way from the margin, and in passing downwards they 

 slip down into the secretion at the bottom, and are prevented from 

 getting out by the hairs. The fluid in this species seems to destroy 

 insects, but it has not yet been proved that it feeds upon them. 



Hooker says that there are two types of pitchers in Sarracenia ; 

 first, those with the mouth open and lid erect, into which rain-water 

 enters easily; and secondly, those with the mouth closed, by the lid, 

 into which rain can hardly obtain ingress. To the first belong such 

 species as Sarracenia purpurea, S. flava, S. rubra, and S. Drummondii. 

 To the second belong Sarracenia variolaris and S. psittacina. In 

 these pitchers he describes four surfaces ; — 1. An attractive surface 

 on the inner part of the lid, with minute honey-secreting glands ; 



Fig. 661. Leaf of a species of Sundew {Drosera rotundifolia), covered with glandular 

 haiis. These hairs secrete a viscid fluid, which often detains insects. The leaves are 

 sometimes seen partially folded. This folding is supposed to he due to irritability. 



