56 Flowers and their Unbidden Guests. 



by repeated partitions in a radial and tangential 

 direction, or they closely resemble in shape a small 

 mushroom; a one-ceUed cylindrical stalk, somewhat 

 contracted above, supporting a lenticular disc which 

 is composed of from sixteen to eighteen wedge- 

 shaped secreting cells, groupe'd, together radially round 

 the upper end of the stem. (Plate I. fig. 4.) The 

 secretion which is discharged by these trichomes is 

 colourless, slimy, and very tenacious. No small animal 

 that comes in contact with it, and once adheres, 

 can ever again get free. The largest insect which 

 I found sticking to this viscid layer and dead was 

 Myrmica Icevinodis NyL, an ant 4 mm. in length. 

 Should larger and stronger insects get on to the 

 leaf-rosette, they can manage to free themselves from 

 the viscid substance. When they have accomplished 

 this they always try to reach the outer edge of the 

 rosette, so as again to get firm land under their feet, 

 and they avoid climbing up the flower-stalk which 

 rises nearly from the centre of the rosette. Darwin's 

 statement that the glandular trichomes on the upper 

 side of the leaves are stimulated to increased secretion 

 by contact with these insects, firmly stuck, or, I might 

 almost say, imbedded in the slime, and that the insects 

 themselves are actually digested,^ I can simply confirm 



^ I must not neglect to record the observation that Diatoma«e» 

 are not digested by the leaves of Pinguicula alpina and vulgcma, 

 indeed that generally they are not killed. I have repeatedly found 



