154 



VEGETABLE LIFE AND WORK. [SECTION 16. 



of the stigma in Mimulus close after a touch. Some are automatic and 

 are connected with dichogamy (339) : the style of Sabbatia and of large- 

 flowered species of Epilobium bends over strongly to one side or turns down- 

 ward when the blossom opens, but slowly erects itself a day or two later. 



476. Extraordinary Movements connected with Capture of In- 

 sects. The most striking cases are those of Drosera and Dionaea ; for an 

 account of which see "How Plants Behave," and Goodale's " Physiological 

 Botany." 



477. The upper face of the leaves of the common species of Drosera, 

 or Sundew, is beset with stout bristles, having a glandular tip. This tip 

 secretes a drop of a clear but very viscid liquid, which glistens like a dew- 

 drop in the sun ; whence the popular name. When a fly or other small 

 insect, attracted by the liquid, alights upon the leaf, the viscid drops are so 

 tenacious that they hold it fast. In struggling it only becomes more com- 

 pletely entangled. Now the neighboring bris- 

 tles, which have not been touched, slowly bend 

 inward from all sides toward the captured in- 

 sect, and bring their sticky apex against its 

 body, thus increasing the number of bonds. 

 Moreover, the blade of the leaf commonly aids 

 in the capture by becoming concave, its sides 

 or edges turning inward, which brings still 

 more of the gland-tipped bristles into contact 

 with the captive's body. The insect per- 

 ishes ; the clear liquid disappears, apparently 



by absorption into the tissue of 

 the leaf. It is thought that the 

 absorbed secretion takes with it 

 some of the juices of the insect 

 or the products of its decompo- 

 sition. 



478. Dionsea muscipula, the 

 most remarkable vegetable fly-trap 

 (Fig. 176, 492), is related to the 

 Sundews, and has a more special 

 and active apparatus for fly- 

 catching, formed of the summit 

 of the leaf. The two halves of this rounded body move as if they were 

 hinged upon the midrib; their edges are fringed with spiny but not 

 glandular bristles, which interlock when the organ closes. Upon the face 

 are two or three short and delicate bristles, whicli are sensitive. They do 

 not themselves move when touched, but they propagate the sensitiveness to 

 the organ itself, causing it to close with a quick movement. In a fresh 



Fio. 492. Plant of Dionaea muscipula, or Venus's Fly-trap, reduced in size. 



