226 DROSERA FILIFORMIS. (Cuar. XIL 
very slowly when particles of meat were placed on the glands, and 
perhaps for my never succeeding in causing any movement by 
repeatedly touching them with a needle. But with all the species of 
the genus this latter stimulus is the least effective of any. Particles 
of glass, cork, and coal-cinders, were placed on the glands of six 
tentacles; and one alone moved after an interval of 2 hrs. 30 m. 
Nevertheless, two glands were extremely sensitive to very small doses 
of the nitrate of ammonia, namely to about 55 of a minim of a solution 
(one part to 5250 of water), containing only as55q of a grain 
(000562 mg.) of the salt. Fragments of flies were placed on two 
leaves near their tips, which became incurved in 15 hrs. A fly was 
also placed in the middle of the leaf; in a few hours the tentacles on 
each side embraced it, and in 8 hrs. the whole leaf directly beneath 
the fly was a little bent transversely. By the next morning, after 
23 hrs., the leaf was curled so completely over that the apex rested 
on the upper end of the footstalk. In no case did the sides of the 
leaves become inflected. A crushed fly was placed on the foliaceous 
footstalk, but produced no effect. 
Drosera spathulata (sent to me by Dr. Hooker).—I made only a 
few observations on this Australian species, which has long, narrow 
leaves, gradually widening towards their tips. The glands cf the 
extreme marginal tentacles are elongated and differ from the others, as 
in the case of Drosera rotundifolia. A fly was placed on a leaf, and 
in 18 hrs. it was embraced by the adjoining tentacles. Gum-water 
dropped on several leaves produced no effect. A fragment of a leaf 
was immersed in a few drops of a solution of one part of carbonate of 
ammonia to 146 of water; all the glands were instantly blackened; 
the process of aggregation could be seen travelling rapidly down the 
cells of the tentacles ; and the granules of protoplasm soon united into 
spheres and variously shaped masses, which displayed the usual 
movements. 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. z4, 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 smal] and 
large insects,—even great flies of the genus Asilus, moths, and _butter- 
flies. ‘The specimen which I examined, sent me by Dr. Hooker, had 
thread-like leaves, from 6 to 12 inches in length, with the wpper surface 
convex and the lower fiat and slightly channelled. The whole convex 
* © American Naturalist,’ Dec. 1873, p. 705. 
