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Show 298 DARWINIAN .A. the same or similar facts. Mrs. Treat, of New Jersey, noticed the habitual infolding of the leaf in the IonO'er- leaved syecies of sundew (American Journal of Science for November, 1871), as 'was then thought for the first time-Roth's and Withering's observations not having been looked up. In recording this, the next year, in a very little book, entitled " How Plants Behave," the opportunity was taken to mention, in the briefest way, the capital discovery of .Mr. Darwin that the leaves of Drosera act differently when different objects are placed upon them, the bristles closing upon a particle of raw meat as upon a living insect, while to a particle of chalk or wood they are nearly inactive. The same facts were independently brought ·out by Mr. A. W. Bennett at the last year's meeting of the British Association for the Advancement of Science, and have been mentioned in the journals. If to these statements, which we may certify, were added some far more extraordinary ones, communicated to the French Academy of Science in May last by M. Zeigler, a stranger story of discrimination on the part of sundew-bristles would be told. But it is safer to wait for the report of the committee to which these marvels were referred, and conclude this sufficiently " strange eventful history " with some details of experiments made last summer by Mrs. Treat, of New Jersey, and published in the December number of the American Naturalist. It is well to note that Mrs. Treat selects for publication the observations of one particular day in July, when the sundew-leaves were unusually active ; for their moods vary with the weath- INSEOTTV.:OROUS PLANTS. 299 er, and also in other unaccountable ways although in general the sultrier days are the most ap;etizing: "At fifteen minutes past ten of the same day I placed bits o~ ra.w beef on ~orne of the most vigorous leaves of Drosera longifoha. Ten mmutes past twelve, two of the leaves had folded around the beef, hiding it from sight. Half-past eleven of tho same ~ay, I placed living flies on the.leaves of D.longifolia. At 12° 48' one of the leaves had folded entirely around its victim, the other leaves bad partially folded, and tho flies had ceased t struggle. By 2° 30' four leaves bad each folded around a fl 0 I t ' d ' y. . . . ne mmeral substances-bits of dry chalk , rna gnesw· , and pebbles. In ·twenty-four hours, neither the ]eaves nor their bristles had made any move like clasping these articles. I wet a piece of chalk in water, and in less than an hour the bristles were curving about it, but soon unfolde<l again, leaving the chalk free on the blade of the leaf." Parallel experiments made on D. rotundifolia, with bits of beef and of chalk, gave the same results as to the action of the bristles; w bile with a piece of raw apple, after eleven hours, "part of the bristles were clasping it but not so closely as the beef,'' and in twenty-four hours "near]; all the bristles were curved toward it, but not many of the glands were touching it." · To make such observations is as easy as it is interesting. Throughout the summer one has ~nly to transfer plants of Drosera from the bogs into pots or pans filled with wet moss-if need be, allowing them to become established in the somewhat Ghanged conditions, or even to put out fresh leaves-and to watch their action or expedite it by placing small flies upon the. disk of the leaves. The more common round-leaved sundew acts as well as the other by its bristles, and the leaf itself is sometimes almost equally prehensile, althou~h in a different way, infolding the whole bor- |
