VENUS'S FLY-TRAP. 57 



the rapid closing of the lobes, simultaneously with the 

 slightest touch ; for the filaments neither secrete 

 nor absorb, and are, in fact, purely sentinels. The 

 tentacles of Drosera when excited become inflected 

 and aggregated, but this property does not extend to 

 the Dioncea filaments. Drops of water falling on 

 them will not cause the lobes to close, nor blowing 

 upon them strongly. Hence the sentinels are not 

 likely to give a false alarm at a shower of rain or a 

 gale of wind. Neither did the rays of the sun, when 

 concentrated upon the filaments to such a degree 

 as to cause them to be scorched and discoloured, 

 produce any movement. 



The minute glands with which the surface of the 

 leaves is studded have the power of secretion and 

 absorption, but they do not secrete until excited 

 by the presence of animal matter. Other objects 

 placed upon the glands will remain quite dry; but, if 

 a fragment of meat, or a crushed fly, is placed on the 

 surface of the expanded lobes after a time the glands 

 will secrete freely. If the lobes are made to close 

 over an insect, then the glands of the whole surface 

 secrete copiously. Two or three instances are given 

 by Mr. Darwin in proof of this i 1 " On one occasion 

 when a leaf was cut open, on which a small cube of 

 albumen had been placed forty-five hours before, 



1 Darwin, " Insectivorous Plants,'' p. 296. 



