74 



THE TISSUES OF PLANTS 



generic name. It is called specifically muscipula, or fly- 

 catcher, with reference to its curious habit of catching flies 

 with its leaves, which are organized expressly for this pur- 

 pose. The leaves have a broad, dilated petiole, and the 

 lamina or blade, which is somewhat circular in outline, is 

 connected by a joint with its top. The margin of the 

 lamina is fringed with a row of stiff bristles or hairs ; three 

 shorter and more slender ones, with swellings at their base, 

 are placed on the upger surface of the leaf, in a triangular 

 position, on either side of the midrib. It is in these last 

 that the irritability chiefly resides. 



Fig. 19. 



Fig. 19 represents a portion of the stem and leaves of Venus's Fly-trap. The 

 leaf consists of two parts, a lamina or blade, I, and a petiole or stalk, p. The 

 two sides of the lamina are united by a sort of hinge, and on the expanded leaf 

 a, the three hairs may be seen on each half of the lamina, which, when touched, 

 cause it to fold up, as represented at 6. 



"When an insect, in traversing the lamina, touches these 

 sensitive hairs, the two sides of the lamina suddenly come 

 into contact ; the bristles with which they are fringed 

 interlace like the fingers of the hands when clasped, and 



