RECORD: Darwin, C. R. 1875. [Letter to Mary Treat, 1874]. Carnivorous Plants.- Vegetable insect traps. Australian Town and Country Journal [Sydney] (23 January), p. 17.

REVISION HISTORY: Transcribed by Christine Chua and edited by John van Wyhe 12.2019. RN1

NOTE: The complete letter is published in Darwin to Mary Treat 22 June 1874, The Correspondence of Charles Darwin, vol. 22, p. 306. On these observations see Insectivorous plants, pp. 310–11.

Darwin cited information from Treat and Canby in Insectivorous plants, pp. 310-11.


[page] 17

Carnivorous Plants. – Vegetable Insect Traps.

I send herewith a communication from a valued correspondent – Mrs Mary Treat of Vineland, N.J. – a keen and trustworthy observer, whose experiments upon the vegetable fly-catcher (Drosera) have already secured for her name a prominent place in the history of carnivorous plants. The experiments here detailed were made in response to a specific inquiry by Mr. Darwin, and they settle the question. These notes were placed at my disposal with the suggestion that they should be offered to The Tribune, and I take pleasure in furthering the author's wishes in this regard. (Asa Gray, in N.Y. Tribune.)

MRS TREAT'S OBSERVATION ON DIONAEA.

In May, 1874, through the kindness of Dr. Wood, of Wilmington, N.C., I recorded over 30 fine plants of Dionaea musicupula. They had been removed with much care, and packed in such a manner that no plant interfered with another, neither were they smothered in a tight box, but slats were nailed across the top so that they could received both light and air.

They reached me looking none the worse for their journey and began capturing prey the next day after their arrival. The upper part of the leaf reminds me of the open jaws of an old fashioned steel-trap, and when any insect alights on the inner surface of this leaf-trap, and touches one or more of the six bristles on its surface, if the leaf is healthy and vigorous, it closes almost as quickly as the steel-trap when anything touches its spring.

From the beginning of May until the last of June, I devoted a large share of each day to these plants. I placed them in separate pots, and numbered each leaf trap and kept a careful record of the closing of each leaf-trap over its prey, and the kind of insect it caught. Mr Darwin in a letter of June, 1874, says:-

"My observation on cultivated plants (of Dionaea) are now complete, and I shall publish them in six or nine months; though they will be of little value compared with those made on the plant in its own country.

I should very much like to hear about one point. Dr Canby says that the same but will catch two or three flies successively. Now I find with cultivated plants that a leaf which has once caught a good-sized insect, though it will open and remain so for a considerable time, has so little power of movement that it rarely is able to catch a second insect or to close over any object. I should very much like to be able to say what the truth is on this head."

To this I am now able to reply that a considerable number of leaves took the third fly, but most of them were not able to wholly digest them. Five leaves digested three flies each, and opened apparently healthy, and were soon apparently ready for another meal, but died soon after closing over the fourth fly. On the other hand some leaves were not able to digest a single fly, as may be seen from my report:-

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Citation: John van Wyhe, editor. 2002-. The Complete Work of Charles Darwin Online. (http://darwin-online.org.uk/)

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