INSECTIVOROUS PLANTS. 299 



er, and also in other unaccountable ways, altliongli in 

 general the sultrier days are the most appetizing : 



"At fifteen minutes past ten of the same day I placed bits 

 of raw beef on some of the most vigorous leaves of Di'osera lon- 

 gifolia. Ten minutes past twelve, two of the leaves had folded 

 around the beef, hiding it from sight. Plalf-past eleven of the 

 same day, I placed living flies on the leaves of I), longifolia. At 

 12° 48' one of the leaves had folded entirely around its victim, 

 the other leaves had partially folded, and the flies had ceased to 

 struggle. By 2° 30' four leaves had each folded around a fly. 

 ... I tried mineral substances — bits of dry chalk, magnesia, 

 and pebbles. In twenty-four hours, neither the leaves nor 

 their bristles had made any move like clasping these articles. I 

 wet a piece of chalk in water, and in less than an hour the bris- 

 tles were curving about it, but soon unfolded again, leaving the 

 chalk free on the blade of the leaf." Parallel experiments made 

 on D. rotundifolia, with bits of beef and of chalk, gave the same 

 results as to the action of the bristles ; while with a piece of raw 

 apple, after eleven hours, "part of the bristles were clasping it, 

 but not so closely as the beef," and in twenty-four hours " nearly 

 all the bristles were curved toward it, but not many of the 

 glands were touching it." 



To make such observations is as easy as it is inter- 

 esting. Throughout the summer one has only to 

 transfer plants of Drosera from the bogs into pots or 

 pans filled with wet moss — if need be, allowing them 

 to become established in the somewhat changed condi- 

 tions, or even to put out fresh leaves — and to watch their 

 action or expedite it by placing small flies upon the 

 disk of the leaves. The more common round-leaved 

 sundew acts as well as the other by its bristles, and 

 the leaf itself is sometimes almost equally prehensile, 

 although in a different way, infolding the whole bor- 



