Cuar. XIL DROSERA FILIFORMIS. 28) 
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 6 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. 34, of a grain, or ‘202 mg.) was too 
powerful, for in the course of 23 hrs. the leaf died. 
Drosera filiformis,—This North American species grows in 
such 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. 30m. 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 
very slightly bent, directly beneath the insect. Perhaps this 
indicates that the blades of vigorous plants would bend over 
vaptured insects, and Dr. Canby informs me that this is the 
case; but the movement cannot be strongly pronounced, as it 
was not observed by Mrs. Treat. 
Drosera binata (or dichotoma).—I am much indebted to Lay 
* ¢ American Naturalist, Dee. 1873, p. 705. 
