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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    to this idea of absorption on the ground that it was not in accordance with our knowledge of the functions of leaves, and to the whole course of the nutrition of vegetables, and therefore was not to be seriously entertained. This argu- ment reminds one of the miserably fallacious arguments against miracles by Hume. It is in both cases a merepetitio principii. All plants are not constituted like the Dionsea, and if it has such a peculiarity in structure, why should it not have a similar one in function ? Other objectors may say, True, the insect is digested and reduced to a semi-fluid pulp, but this is simply for the purpose of allowing it to run down the channelled petiole, and so of reaching the absorbent roots of the plant. Mr Canby at one time thought that such was the case, but he afterwards discovered his mistake. Two answers may be given to the above objection. 1. In a healthy Dionsea, where the natural food of the plant has been taken and in the normal amount, no fluid does run down the petiole. Three flies were placed on three leaves of Dionsea, and pieces of litmus were attached to the petioles on Sept. 26 ; and on Sept. 28, at 4 p.m., the litmus was not in the least degree reddened. On Sept. 29 the same, and so on Oct. 1 and Oct. 3, and yet on this latter date one of the leaves was opened, and a considerable quantity of fluid of an acid nature was found. This was on the seventh day. 2. The second is that the leaf is found quite dry on the surface, with only the slightest indication, if even that, of remains, and if we open the leaf from time to time we can see the process of change going on, and the gradual diminution of the amount. Example, piece of raw meat on leaf of Dionsea on July 1. On July 18 there seemed very little difference on the external appearance from what had been noticed on the 4th, when it was pale, like veal, and partially digested; but on the 23d the beef was found in a soft thin pulp and in small bulk. On the 24th almost all gone, and on the 25th small thin dry flakes are all that remain. In this case the whole process of digestion and absorp- tion took twenty-four days, but the absorption seemed to go on at a much more rapid rate towards the end.
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