# From Francis Darwin   [25–7 May 1880]1

My dear Father,

I hope you got a telegram about Convulvulus.2 The thing I found on working out the measurements is that they told nothing at all. A day is too long a period—the bits of stem which are growing well grow at a tremendous rate for a couple of days & then almost stop so that I could never get any fair comparisons3

Today I am measuring 4 plants every 4 hrs 7 am—11—3—7 pm   I can measure to $\frac{1}{2}$ mm & I think with the rapid growth of 1 to 2$\frac{1}{2}$ mm pr hour I ought to make out. They have alternate 4 hr periods of light & dark— If I see no good results today I shall shut up.

Please give my love to Sara & say I hope it will not matter my coming later instead of when I ought to   I think I must go to Brittany by a boat leaving S’hampton Monday night4   I wonder if Ubbadub remembers S’hampton at all.5 | Yrs affec F. D.

I shall certainly come on Friday6

## Footnotes

The date is established by the references to CD’s and Francis Darwin’s visits to Southampton; Francis must have written after Emma and CD’s departure for Southampton on 25 May and before his arrival there on 28 May (see nn. 4 and 6, below).
The telegram has not been found. Convolvulus is the genus of bindweed. On 4 May 1880, CD recorded that he was working on sleep in cotyledons of C. major (a synonym of Ipomoea purpurea, common morning-glory; DAR 209.9: 12). Another undated note, about the growth of C. major in sand, records a task for Francis: ‘Get Frank to give prescription about the nutritive fluids—’ (DAR 68: 21).
Francis Darwin appears to have been trying to measure the rate of growth of plants relative to the amount of light present; he was possibly using the auxanometer (a self-recording instrument for measuring growth) built by Horace Darwin in 1876 (F. Darwin and Acton 1894, p. 140 n. 2).
CD stayed with Sara and William Erasmus Darwin in Southampton from 25 May to 8 June 1880 (CD’s ‘Journal’ (Appendix II)). Emma Darwin’s diary records that Francis Darwin left for Brittany on Monday 31 May 1880 (DAR 242).
Ubbadub was a pet name for Francis’s 3-year-old son, Bernard Darwin; Bernard and Francis lived with CD and Emma Darwin, and had accompanied them to Southampton on their previous annual visit (letter from Emma Darwin to H. E. Litchfield, [10 May 1879] (DAR 219.9: 196)).
Emma Darwin’s diary records that Francis Darwin arrived in Southampton on Friday 28 May 1880 (DAR 242).

## Bibliography

Darwin, Francis and Acton, Edward Hamilton. 1894. Practical physiology of plants. Cambridge: Cambridge University Press.

## Summary

Hopes CD got telegram about Convolvulus. Is measuring plants every four hours. Will go to Brittany by boat from Southampton on Monday night.

## Letter details

Letter no.
DCP-LETT-12616F
From
Francis Darwin
To
Charles Robert Darwin
Source of text
DAR 274.1: 65
Physical description
ALS