Only a brief chapter is devoted to Dionaea of North Carolina, the Venus’s fly-trap, albeit, “from the rapidity and force of its movements, one of the most wonderful in the world.”  It is of the same family as the sundew; but the action is transferred from tentacles on the leaf to the body of the leaf itself, which is transformed into a spring-trap, closing with a sudden movement over the alighted insect.  No secretion is provided beforehand either for allurement or detention; but after the captive is secured, microscopic glands within the surface of the leaf pour out an abundant gastric juice to digest it.  Mrs. Glass’s classical directions in the cook-book, “first catch your hare,” are implicitly followed.

Avoiding here all repetition or recapitulation of our former narrative, suffice it now to mention two interesting recent additions to our knowledge, for which we are indebted to Mr. Darwin.  One is a research, the other an inspiration.  It is mainly his investigations which have shown that the glairy liquid, which is poured upon and macerates the captured insect, accomplishes a true digestion; that, like the gastric juice of animals, it contains both a free acid and pepsin or its analogue, these two together dissolving albumen, meat, and the like.  The other point relates to the significance of a peculiarity in the process of capture.  When the trap suddenly incloses an insect which has betrayed its presence by touching one of the internal sensitive bristles, the closure is at first incomplete.  For the sides approach in an arching way, surrounding a considerable cavity, and the marginal spine-like bristles merely intercross their tips, leaving intervening spaces through which one may look into the cavity beneath.  A good idea may be had of it by bringing the two palms near together to represent the sides of the trap, and loosely interlocking the fingers to represent the marginal bristles or bars.  After remaining some time in this position the closure is made complete by the margins coming into full contact, and the sides finally flattening down so as to press firmly upon the insect within; the secretion excited by contact is now poured out, and digestion begins.  Why these two stages?  Why should time be lost by this preliminary and incomplete closing?  The query probably was never distinctly raised before, no one noticing anything here that needed explanation.  Darwinian teleology, however, raises questions like this, and Mr. Darwin not only propounded the riddle but solved it.  The object of the partial closing is to permit small insects to escape through the meshes, detaining only those plump enough to be worth the trouble of digesting.  For naturally only one insect is caught at a time, and digestion is a slow business with Dionaeas, as with anacondas, requiring ordinarily a fortnight.  It is not worth while to undertake it with a gnat when larger game may be had.  To test this happy conjecture, Mr. Canby was asked, on visiting the Dionaeas in their native habitat, to collect early in the season a good series of leaves in the act of digesting naturally-caught insects.  Upon opening them it was found that ten out of fourteen were engaged upon relatively large prey, and of the remaining four three had insects as large as ants, and one a rather small fly.