CALYCIFLORi?^ 227 



surface only, the leaves being smooth and without 

 hairs beneath. These filaments are not of equal 

 length, but look like a number of pins stuck in a pin- 

 cushion, those in the middle being erect and very 

 short ; the marginal ones are longer, with some of 

 intermediate size between. There are in all about 

 two hundred on each leaf. The tip of the filament 

 is a gland. It secretes a clear, thick, sticky sub- 

 stance or fluid, which is capable of being drawn out 

 into threads. These filaments are sensitive to the 

 touch and to hard substances, but not to the influence 

 of weather, rain, etc. When touched, a sticky fluid 

 is poured forth. This is an acid, but not of the 

 nature of pepsin. If an insect should alight upon 

 one of these glistening filaments or tentacles, mis- 

 taking them for honey-secreting glands, the juice 

 flows, and then a sort of ferment is produced of the 

 nature of pepsin. The plant thus, in withholding 

 the latter substance, according to the nature of the 

 stimulus, exhibits selective choice, due to a fine 

 adaptation to the mode of obtaining its animal food. 

 This selective power is one of the most marked 

 phases of sensitiveness in the plant world. Insects 

 that do settle upon the tentacles, especially small 

 flies, midges, ants, etc., become entangled in the 

 mesh of filaments and are caught by the sticky juice, 

 and are unable to fly away. 



By degrees they are overwhelmed by it and become 

 suffocated and die. The tentacles in the Sundew 

 move in response to contact with animal matter. 



