252 DIONZA MUSCIPULA. [Ome XIII. 
minute insect, and several additional days or weeks in 
afterwards recovering its sensibility; inasmuch as a minute 
insect would afford but little nutriment. It would be far 
better for the plant to wait for a time until a moderately 
large insect was captured, and to allow all the little ones to 
escape ; and this advantage is secured by the slowly inter- 
crossing marginal spikes, which act like the large meshes of 
a fishing-net, allowing the small and useless fry to escape. 
As I was anxious to know whether this view was correct— 
and as it seems a good illustration of how cautious we ought 
to be in assuming, as I had done with respect to the marginal 
spikes, that any fully developed structure is useless—I 
applied to Dr. Canby. He visited the native site of the 
plant, early in the season, before the leaves had grown to 
their full size, and sent me fourteen leaves, containing 
naturally captured insects. Four of these had caught rather 
small insects, viz. three of them ants, and the fourth a rather 
small fly, but the other ten had all caught large insects, 
namely, five elaters, two chrysomelas, a curculio, a thick and 
broad spider, and a scolopendra. Out of these ten insects, 
no less than eight were bevtles,* and out of the whole four- 
teen there was only one, viz. a dipterous insect, which could 
readily take flight. Drosera, on the other hand, lives chiefly 
on insects which are good flyers, especially Diptera, caught 
by the aid of its viscid secretion. But what most concerns 
us is the size of the ten larger insects. Their average length 
from head to tail was +256 of an inch, the lobes of the leaves 
being on an average *53 of an inch in length, so that the 
insects were very nearly half as long as the leaves within 
which they were enclosed. Only a few of these leaves, 
therefore, had wasted their powers by capturing small prey, 
though it is probable that many small insects had crawled 
over them and been caught, but had then escaped through 
the bars. 
The Transmission of the Motor Impulse, and means of Move- 
* Dr. Canby remarks (‘Gardener’s elaters, for the five which I examined 
Monthly,’ Aug. 1868), “as a general were in an extremely fragile and 
thing beetles and insectsof that kind, empty condition, as if all their in- 
though always killed, seem to be ternal parts had been partially di- 
too hard-shelled to serve as food, gested. Mrs. Treat informs me that 
and after a short time are rejected.” the plants which she cultivated in 
I am surprised at this statement, at New Jersey chiefly caught Diptera. 
least with respect to such beetles as 
