SUNDEW AND ITS TENTACLES 



will bend over towards it through an angle of forty-five 

 degrees, and it takes them ten minutes to bend over ninety 

 degrees. 



There is something rather horrible in the sight of a large 

 insect struggling with these slow, remorseless, well-aimed 

 tentacles ; most people free the insect unless, at least, it hap- 

 pens to be a midge. The point which is so difficult to 

 understand is to know how those untouched tentacles know 

 that the insect is there and exactly where it is. There is no 

 doubt that they do know, for they behave exactly as if they 

 were the arms of a spider. 



If you put two insects on either side of the middle of the 

 leaf, half the tentacles will pin down one and the other half 

 will deal with the other insect. 



At the same time acids and ferments are poured out which 

 digest the insect. It takes about two days for a leaf to 

 finish off an insect, and then the tentacles again unclose. 



Moreover it is difficult to deceive those tentacles. They 

 will bend in for the tiniest piece of useful substance; for 

 instance, a length of one-seventy-fifth of an inch of woman''s 

 hair will make them secrete digestive fluid. One millionth 

 part of a pound of ammonium phosphate will also produce 

 secretion. But a shower of heavy rain, grains of sand, or 

 other useless material, will not cause any secretion, and even 

 if they do bend in a little, they soon discover their mistake 

 and stand out again. If you try the same experiment under 

 a bell-glass from which the oxygen has been withdrawn by an 

 air-pump, nothing happens ; or if you chloroform the Sundew 

 it will pay no attention to small pieces of meat until it re- 

 covers from the effects of the chloroform. 



When these Droseras are taken to a greenhouse and ex- 

 periments are made on them, they run into very great 



350 



