1 1 6 On Flowers and Insects. 



4. Mr. Darwin, however, has not only made it 

 clear from theoretical considerations, but has also 

 proved it, in a variety of cases, by actual experiment. 

 More recently Fritz Miiller has even shown that in 

 some cases pollen, if placed on the stigma of the 

 same flower, has no more effect than so much in- 

 organic dust. 



In by far the majority of cases, the relation 

 between flowers and insects is one of mutual ad- 

 vantage. In some plants, however as, for instance, 

 in our Common Sundew we find a very different 

 state of things, and the plant catches and devours 

 the insects. The first observation on insect-eating 

 flowers was made about the year 1768 by our 

 countryman Ellis. He observed that in a certain 

 North American plant the leaves have a joint in 

 the middle, and thus close over, kill, and actually 

 digest any insect which may alight on them. 



5. In our common Sundew (fig. 25) the rounded 

 leaves are covered with hairs, which are swollen 

 and glutinous at the tip. Of these hairs there 

 are on an average about 200 on a full-sized leaf. 

 The tips of the hairs are each surrounded by a 

 drop of an exceedingly viscid solution, which, 

 glittering in the sun, has given rise to the name of 

 the plant. If any object be placed on the leaf, 

 these glandular hairs slowly fold over it, and en- 

 close it. If, for instance, any small insect alights 

 on the leaf it becomes entangled in the glutinous 

 secretion, the glands close over it, their secretion is, 



