RECORD: Darwin, C. R. 1875. [Letters to J. Fayrer on cobra poison and Drosera] In T. L. Brunton and J. Fayrer, On the nature and physiological action of the Crotalus-poison as compared with that of Naja tripudians and other Indian venomous snakes; also investigations into the nature of the influence of Naja- and Crotalus-poison on ciliary and amoeboid action and on Vallisneria, and on the influence of inspiration of pure oxygen on poisoned animals. [Read 18 February 1875] Proceedings of the Royal Society of London 23 (1874-5): 261-79, pp. 273-4.

REVISION HISTORY: Transcribed by John van Wyhe. RN1

NOTE: See Correspondence of Charles Darwin vol. 22, p. 310.

[page] 273

The following communications were received from Mr. C. Darwin on the action of some of the same cobra-poison on vegetable protoplasm: —

You will perhaps like to hear how it acted on Drosera. I made a solution of 1/4 gr. to 3ij of water. A minute drop on a small pin's head

[page] 274

acted powerfully on several glands, more powerfully than the fresh poison from an adder's fang.

I also immersed three leaves in 90 minims of the solution; the tentacles soon be­came inflated and the glands quite white, as if they had been placed in boiling water. I felt sure that the leaves were killed; but after 8 hours' immersion they were placed in water, and after about 48 hours reexpanded, showing that they were by no means killed. The most surprising circumstance is, that, after an immersion of 48 hours, the protoplasm in the cells was in unusually active movement. Now, can you inform me whether this poison, if diluted, arrests the movement of vibratile cilia?

I dissolved 1/2 gr. (of cobra poison) in 3j of water, so that I was able to immerse two leaves. It acted as before, but more energetically; and I observed more clearly, this time, that the solution makes the secretion round the glands cloudy, which I have never before observed. But here comes the remarkable point; after an immersion of 48 hours, the protoplasm within the cells incessantly changes form, and I never saw it on any other occasion so active. Hence I cannot doubt that this poison is a stimulant to the protoplasm; and I shall be very curious to find out in your papers whether you have tried its action on the cilia and on the colourless corpuscles of the blood. If the poison does arrest their movement, it will show that there is a profound difference between the protoplasm of animals and of this plant. Therefore if you try any further experiments I hope that you will be so kind as to inform me of the results. I may add that I tried at first 1 gr. to the 3j, as that is my standard strength for all substances.

It is certainly very remarkable that the poison should act so differendy on the cilia and on the protoplasm of Drosera. After the 48 hours' immersion, I placed the two leaves in water and they partially reexpanded. I thought that the whitened glands were perhaps killed; but those of one leaf which I tried with carbonate of ammonia absorbed it, and the protoplasm was affected in the usual manner. I am very mush surprised at the action of the poison on the viscid secretion from the glands, which it coagulates into threads and bits of membrane, with much granular matter. Have you observed whether the poison affects in any marked manner mucus or other such secretions?

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