To Francis Darwin 26 June [1878]1
Down, | Beckenham, Kent. | Railway Station | Orpington. S.E.R.
June 26th
My dear F.
I have been greatly interested by the scientific part of your letter & we have all been amused by the non-scientific.2 If you have spare time (but not otherwise) I shd like to know from your own researches whether in oat seedlings (say or inch high) whether there is chlorophyll,— So as to make sure that the bending is to find a passage to light for future use.—3
I quite overlooked in Sachs about radicles in Cieslokis’ experiments being dry.—
Keep extract about his statement of sliced radicles turning from the cut side.—4 Please let me hear generic name of plant— hygrometrica: perhaps I cd. borrow spec. from Kew.5
I wonder what made Sachs think about bloom protection against insects: I suppose you mentioned our results with cabbages & Sea-Kale.—6
If you can make it out read the enclosed memorandum & tell me what you think about it.— I fear from reading McNab Pfeffer’s book must be studied.—7 It seems to me that the cotyledons of Oxalis offer a most promising field for study, as in some species, they move vertically up,—in others vertically down—in others only a little movement at night.8
Your affect. old Father | C. Darwin
[Enclosure]
June 25th 1878. The short petioles of the Cots. of Cassia are enlarged, transversely wrinkled & formed of tissue appearing different from that of lamina & Hypocotyl.— How is Oxalis valdiviana & rosea or floribunda??
I neglected to observe with Cassia whether when Cots. Horizontal upper surface of petiole is transversely wrinkled.—
I have looked at Cots. of Oxalis floribunda & there seems to be a semicircular pale-coloured pulvinus on upper surface formed of smaller cells; but it tired me too much to look carefully.— Now on O. corniculata the cots of which raise only 45° I can see no pulvinus.— This very important showing that pulvinus developed in same genus.9
Footnotes
Bibliography
Ciesielski, Theophil. 1871. Untersuchungen über die Abwärtskrümmung der Wurzel. Inaugural-Dissertation welche mit Genehmigung philosophischen Facultät der königl. Universität zu Breslau zur Erlangung der Doctorwürde. Breslau: R. Nischkowsky.
McNab, William Ramsay. 1878. Botany: outlines of morphology and physiology. London: Longmans, Green, and Co.
Pfeffer, Wilhelm. 1875. Die periodische Bewegungen der Blattorgane. Leipzig: Verlag von Wilhelm Engelmann.
Summary
Asks questions related to movement in plants. The cotyledons of Oxalis offer a promising field for study.
Wonders why Julius von Sachs thinks bloom is a protection against insects.
Encloses notes on the cotyledons of Oxalis species.
Letter details
- Letter no.
- DCP-LETT-11570
- From
- Charles Robert Darwin
- To
- Francis Darwin
- Sent from
- Down
- Source of text
- DAR 211: 29–30
- Physical description
- ALS 4pp, encl Amem 1p
Please cite as
Darwin Correspondence Project, “Letter no. 11570,” accessed on 26 September 2022, https://www.darwinproject.ac.uk/letter/?docId=letters/DCP-LETT-11570.xml