CHAP. XII. DEOSERA FILIFORMIS. 2S1 



ments. Half a minim of a solution of one part of nitrate of 

 ammonia to 146 of water was next placed on the centre of a leaf ; 

 after G hrs. some marginal tentacles on both sides were inflected, 

 and after 9 hrs. they met in the centre. The lateral edges of the 

 leaf also became incurved, so that it formed a half-cylinder ; but 

 the apex of the leaf in none of my few trials was inflected. The 

 above dose of the nitrate (viz. -g^ of a grain, or '202 mg.) was too 

 powerful, for in the course of 23 hrs. the leaf died. 



Dyoseni filiformis. This 'North American species grows in 

 siif ) abundance in parts of New Jersey as almost to cover the 

 ground. It catches, according to Mrs. Treat,* an extraordinary 

 number of small and large insects, even great flies of the 

 genus Asilus, moths, and butterflies. The specimen which I 

 examined, sent me by Dr. Hooker, had thread-like leaves, from 

 6 to 12 inches in length, with the upper surface convex and 

 the lower flat and slightly channelled. The whole convex 

 surface, down to the roots for there is no distinct footstalk is 

 covered with short gland-bearing tentacles, those on the margins 

 being the longest and reflexed. Bits of meat placed on the 

 glands of some tentacles caused them to be slightly inflected in 

 20 m. ; but the plant was not in a vigorous state. After 6 hrs. 

 they moved through an angle of 90, and in 24 hrs. reached 

 the centre. The surrounding tentacles by this time began to 

 curve inwards. Ultimately a large drop of extremely viscid, 

 slightly acid secretion was poured over the meat from the 

 united glands. Several other glands were touched with a little 

 saliva, and the tentacles became incurved in under 1 hr., and 

 re-expanded after 18 hrs. Particles of glass, cork, cinders, 

 thread, and gold-leaf, were placed on numerous glands on two 

 leaves ; in about 1 hr. four tentacles became curved, and four 

 others after an additional interval of 2 hrs. 30 m. I never once 

 succeeded in causing any movement by repeatedly touching the 

 glands with a needle ; and Mrs. Treat made similar trials for me 

 with no success. (Small flies were placed on several leaves near 

 their tips, but the thread-like blade became only on one occasion 

 vf>ry slightly bent, directly beneath the insect. Perhaps this 

 indicates that the blades of vigorous plants would bend ovei 

 captured insects, and Dr. Cauby informs me that this is the 

 case ; but the movement cannot be strongly pronounced, as it 

 was not observed by Mrs. Treat. 



JJrosera binata (or dichotoma). I am much indebted to Ladj 



' American Naturalist,' Dec. 1873, p. 705. 



