Chap. XV. STRUCTURE OF LEAVES. 333 



are linear, miicli attenuated towards their tips, and 

 several inches in length. The upper surface is con- 

 cave, the lower convex, with a narrow channel down 

 the middle. Both surfaces, with the exception of the 

 channel, are covered with glands, supported on pedicels 

 and arranged in irregular longitudinal rows. These 

 organs I shall call tentacles, from their close resem- 

 blance to those of Drosera, though they have no power 

 of movement. Those on the same leaf differ much in 

 length. The glands also differ in size, and are of a 

 bright pink or of a purple colour; their upper sur- 

 faces are convex, and the lower flat or even concave, 

 so that they resemble miniature mushrooms in appear- 

 ance. They are formed of two (as I believe) layers 

 of delicate angular cells, enclosing eight or ten larger 

 cells with thicker, zigzag walls. Within these larger 

 cells there are others marked by spiral lines, and 

 apparently connected with the spiral 

 vessels which run up the green multi- 

 cellular pedicels. The glands secrete ^^"^^ 

 large drops of viscid secretion. Other p ^ ^ ^" -1 

 glands, having the same general 

 appearance, are found on the flower- ^ 

 peduncles and calyx. ) 



Besides the glands which are borne >^ ' 



on longer or shorter pedicels, there '^ , ^^'J 

 are numerous ones, both on the upper tj^ u\^ 

 and lower surfaces of the leaves, so 

 small as to be scarcely visible to the '^^^- ^^^ 



naked eye. They are colourless and tanicum.) 



almost sessile, either circular or oval P^^-t of leaf, enlarged 



' ^ Beven times, shovv- 



in outline ; the latter occurring chiefly i"s lo^^r surface. 

 on the backs of the leaves (fig. 14). 

 Internally they have exactly the same structure as 

 the larger glands which are supported on pedicels ; 



