44 Chapters in Modern Botany CHAP. 



whitish flowers. Each leaf consists of a long narrow 

 stalk, expanded into a more or less circular blade, the 

 edges and surface of which bear scores of club-like " hairs " 

 or " tentacles," apparently tipped with dew. These hairs 

 are complex structures ; the head of each is glandular and 

 well supplied with water-pipes (spirally thickened wood- 

 fibres or " tracheides ") ; it is the viscid secretion of the 

 gland which makes the apparent dewdrop. 



These hairs or tentacles, then, are sensitive, mobile, 

 digestive, and absorptive most marvellous little structures, 

 indifferent to the drops of rain which often fall upon them, 

 but responsive to the stimulus of a midge. An insect unwary 

 or deluded alights on the leaf, and is forthwith entangled ; 

 as it struggles the secretion becomes more abundant. 

 The tentacles too bend down upon the entangled midge; 

 first one, and in a few minutes another, and another, till 

 all the two hundred may close upon the prey like so many 

 slow merciless fingers. The leaf may become more con- 

 cave, and after complete closure looks like a closed fist. 

 As the result of the secretion the booty is digested and the 

 products of digestion absorbed. 



So far the usual general description of the sundew ; but 

 now let us take up Darwin's Insectivorous Plants, and read 

 up the details, for there is no more characteristic example 

 of his patient elaborate way of working than his account of 

 the sundew. 



Further Details of Functional or Structural Interest. 

 There are on an average about two hundred glandular 

 tentacles. The stalk of each has the essential structure 

 of a leaf: a small " fibro-vascular bundle," consisting 

 mainly of spiral tracheides, runs up the centre, and is 

 surrounded by a layer of elongated cells lined by a thin 

 layer of colourless circulating protoplasm, and filled with 

 a purplish fluid. The glandular head of the tentacle con- 



