32 FREAKS OF PLANT LIFE. 



the cause of the inflection, than when a small insect, 

 or a fragment of meat, has been the exciting cause. 

 These facts have been proved by numerous experi- 

 ments, which place them beyond question. First, 

 that the tentacles are sensitive (if we may use that 

 expression) to the sustained pressure of one millionth 

 part of a grain. That they will respond to such 

 pressure, and bend towards the centre of the leaf 

 That this irritation will also be communicated to 

 neighbouring tentacles, which will bend in the same 

 direction. And that after this operation is performed 

 the inflected tentacles will return to their former 

 position. If we suppose, then, that a minute insect 

 has fallen or alighted upon one, or more, of the outer 

 tentacles, it will in the course of ten seconds be 

 moving towards the centre, whither it will ultimately 

 be carried, whilst the surrounding tentacles will also 

 follow in the bending movement, until all are closed 

 over the captive insect. But, it may be asked, are we 

 assured that the first inward movement of the 

 tentacles will not alarm the insect and cause it to 

 take flight .'' It might do so if this were not provided 

 against by the viscid secretion with which the glands 

 arc covered, and which increases in quantity with the 

 inward movement of the tentacles. This secretion is 

 so tenacious that it may be drawn out in strings, and 

 if once a small insect alights upon it, it struggles in 

 vain to get free. It is, in fact, a kind of birdlime, 



