THE BUTTERWORTS 



213 



of these glands on a square centimetre of the leaf, 

 and consequently a plant with a rosette of six to nine 

 leaves is estimated to possess about half a million. 



In the photograph on Plate XLL, Fig. 2, two rosettes 

 of Pinguicula leaves are seen, thriving on a cushion of 

 damp moss, which is itself attached to the root of a 

 Spruce Fir. It will be noticed that numerous remains 

 of dead insects, chiefly flies, occur on the leaves of the 



FIG. XIX. The Common Butterwort (Pinguicula vulgaris, Linn.). 



1. Transverse section of a leaf, showing the glands on the upper surface. 

 Somewhat enlarged. 2. A side view of a gland. Much enlarged. 



3. A surface view of a gland. Much enlarged. 



larger rosettes, and in one case, on the uppermost 

 leaf of the smaller rosette, growing below and slightly 

 to the right of the larger rosette, the remains of a 

 moth are clearly seen. 



This plant has the power, not only of catching 

 small insects on its leaves, but of digesting and absorb- 

 ing them. What happens is briefly as follows. The 

 glandular hairs of the upper surface secrete a sticky 

 fluid, which attracts insects, probably under the 



