310 DARWimANA. 



is full of interest as a physiological research, and is a 

 model of its kind, as well for the simplicity and direct- 

 ness of the means employed as for the clearness with 

 which the results are brought out — results which any 

 one may verify now that the way to them is pointed 

 out, and which, surprising as they are, lose haK their 

 wonder in the ease and sureness with which they seem 

 to have been reached. 



Kather more than half the volume is devoted to 

 one subject, the round-leaved sundew {Drosera rotun- 

 difolia), a rather common plant in the northern tem- 

 perate zone. That flies stick fast to its leaves, being 

 limed by the tenacious seeming dew-di'o^^s which stud 

 its upper face and margins, had long been noticed in 

 Europe and in this country. We have heard hunters 

 and explorers in our IS^orthern woods refer with satis- 

 faction to the fate which in this way often befalls one 

 of their plagues, the black fly of early summer. And 

 it was known to some observant botanists in the last 

 century, although forgotten or discredited in this, that 

 an insect caught on the viscid glands it has happened 

 to alight upon is soon fixed by many more — not mere- 

 ly in consequence of its struggles, but by the sponta- 

 neous incurvation of the stalks of surrounding: and 

 untouched glands ; and even the body of the leaf had 

 been observed to incmwe or become cup-shaped so as 

 partly to involve the captive insect. 



Mr. Darwin's peculiar investigations not only con- 

 firm all this, but add greater wonders. They relate to 

 the sensitiveness of these tentacles^ as he prefers to call 

 them, and the mode in which it is manifested ; their 

 power of absorption ; their astonishing discernment of 



