CHAP. Xlli. MANNER OF CAPTURING INSECTS. 311 



who observed in the United States a large number of 

 plants which, although not in their native site, were 

 probably more vigorous than nay plants, informs 

 me that he has "several times known vigorous leaves 

 to devour their prey several times ; but ordinarily 

 twice, or, quite often, once was enough to render them 

 unserviceable." Mrs. Treat, wlio cultivated many 

 plants in New Jersey, also informs me that "several 

 leaves caught successively three insects each, but most 

 of them were not able to digest the third fly, but died 

 in the attempt. Five leaves, however, digested each 

 three flies, and closed over the fourth, but died soon 

 after the fourth capture. Many leaves did not digest 

 even one large insect." It thus appears that the 

 power of digestion is somewhat limited, and it is 

 certain that leaves always remain clasped lor many 

 days over an insect, and do not recover their power of 

 closing again for many subsequent days. In this 

 respect Diomea differs from Drosera, which catches 

 and digests many insects after shorter intervals of 

 time. 



We are now prepared to understand the use of the 

 marginal spikes, which form so conspicuous a feature 

 in the appearance of the plant (fig. 12, p. 287), and 

 which at first seemed to me in my ignorance useless 

 appendages. From the inward curvature of the lobes 

 as they approach each other, the tips of the marginal 

 spikes first intercross, and ultimately their bases. 

 Until the edges of the lobes come into contact, elon- 

 gated spaces between the spikes, varying from the -^ 

 to the -fV of an inch (TG9o to 2'54 mm.) in breadth, 

 according to the size of the leaf, are left open. Thus 

 an insect, if its body is not thicker than these mea- 

 surements, can easily escape between the crossed 

 spikes, when disturbed by the closing lobes and in 



21 



