of its two lobes, and retained this unusual position for the next two days.  A third case offers the strongest exception which I have observed; a leaf, after remaining clasped for an unknown time over a fly, opened, and when one of its filaments was touched, closed, though rather slowly.  Dr. Canby, [page 311] who observed in the United States a large number of plants which, although not in their native site, were probably more vigorous than my 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, who 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 for many days over an insect, and do not recover their power of closing again for many subsequent days.  In this respect Dionaea 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, elongated spaces between the spikes, varying from the 1/15 to the 1/10 of an inch (1.693 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 measurements, can easily escape between the crossed spikes, when disturbed by the closing lobes and in- [page 312] creasing darkness; and one of my sons actually saw a small insect thus escaping.  A moderately large insect, on the other hand, if it tries to escape between the bars will surely be pushed back again into its horrid prison with closing walls, for the spikes continue to cross more and more until the edges of the lobes come into contact.  A very strong insect, however, would be able to free itself, and Mrs. Treat saw this effected by a rose-chafer (Macrodactylus subspinosus) in the United States.  Now it would manifestly be a great disadvantage to the plant to waste many days in remaining clasped over a 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 intercrossing marginal spikes, which act like the large meshes of a fishing-net, allowing the small and useless fry to escape.