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Darwin Correspondence Project

From Lawson Tait   6 November [1875]1

7, Great Charles St. | Birmingham.

Novr. 6

My Dear Sir,

I have made a very curious discovery within the last few days. My “Droserin” is a compound substance containing the digestive principle which I propose to designate by that name and another substance so deliquescent that it cannot be kept in a dry condition and has the peculiar property, like glycerine, of wandering about & wetting everything2 It is the substance which kills the flies by enabling the water to enter their tracheae.

Plain water does not wet flies. They swim for days on its surface. But water containing this substance wets & kills flies in a few minutes.

What shall I call it? I wish your name would allow its being ‘coined’ into “Darwinin”

I have polished up my greek to get a term descriptive of its peculiar properties, but I am at a loss

I have no doubt your son Francis3 is a good Grecian & can help me.

This substance also accounts for the never-drying nature of the secretion

Yours ever | Lawson Tait


The year is established by the reference to Tait’s experiments on digestion in plants (see n. 2, below).
Tait was trying to isolate substances in the digestive fluid of insectivorous plants. On ‘droserin’, see the letter from Lawson Tait, 15 July [1875] and n. 5.


Composition of "Droserin" [see 10015].

Letter details

Letter no.
Robert Lawson (Lawson) Tait
Charles Robert Darwin
Sent from
Source of text
DAR 178: 21
Physical description
ALS 4pp

Please cite as

Darwin Correspondence Project, “Letter no. 10244,” accessed on 1 April 2023,

Also published in The Correspondence of Charles Darwin, vol. 23