Experiments on Dionaea muscipula (Venus' fly-trap) / by Thos. A.G. Balfour.

  • Balfour Thomas A. G. (Thomas Alexander Goldie), 1825-1895.
Date:
1875
Catalogue details

Licence: Public Domain Mark

Credit: Experiments on Dionaea muscipula (Venus' fly-trap) / by Thos. A.G. Balfour. Source: Wellcome Collection.

Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.

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    On July 22, to test whether the influence might not be transmitted from the root, I cut the midrib of the petiole quite through at about one-third of its length from the leaf; the wings of the petiole were left entire. The leaf remained open after this operation, but was closed on irritation. July 23.—Leaf open to only half the lashes to-day. July 24.—At 3 p.m. leaf half open, closed on irritation It continued to do so on July 27 and August 1. Dutrochet, in reference to the Sensitive Plant, believes that there are two kinds of cells, the one exhibiting the power of contraction and the other the power of distension, and that these are situated, though in a reverse order, at the swelling of leaflets and the pulvinus of the petiole, the contractile cells being above in the one case and below in the other, and consequently the place of irritation is, in the one case, above, and, in the other, in the pulvinus below; and as the over distension of the other kind of cells is, in his view, the immediate cause of the movement, the leaflets are forced to take an upward direction, while the petiole falls down ; and he thinks that his view is confirmed by the effects of cutting the lower part of the pulvinus, which would interrupt the process on which his theory is founded. Dr Carpenter adopts these views, and applies them to the explanation of the closing of the Dionsea leaf. But whatever we may think as to the Sensitive Plant,* it cer- tainly seems to fail in the Dionaea; for I have in two instances cut off a considerable slice from the lower portion of the midrib and yet the leaf has closed, so that some other explanation than that of contractile and distensible cells is here necessary. Again, if we take the case of the Droseras, which are congeners of the Dionsea, we find that in D. longifolia, Whiiakerii, rotundifolia, &c., the mode of con- * I have tried some experiments on the upper and lower parts of the attachment of the petiole, and I must own that, though they have been far from being quite confirmatory of >Dutrochet’s view, there was one instance which seemed to support it: a portion of the upper part of the petiole was cut aw,ay, and some days afterwards on touching the pulvinus the petiole did not descend to the same length as the others did, though from the weakening of the base of the petiole we should have expected it to have gone down further than any of them.