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Darwin Correspondence Project

From H. C. Watson   20 September 1861

Thames Ditton S.W.

Sept 20th 61

Dear Mr Darwin

I have some recollection of intimating a distrust of Mr. Sidebotham’s recorded experiments on Primroses, &c. though I cannot now hit upon the intimation.—1 However, I find his two papers in Phytolst.   The first (Vol. 2, p. 887)2 is of no moment, except as calling forth a P.S. mem. by Newman or Luxford, to the effect that the Primula Jacquinii—(Bardfield oxlip) comes true from seed in second & third generations.3 I have again looked over his second paper, & am still unwilling to rely on his accuracy;4 & likely enough the objections which I should now make to the record, are such as were made before, & fell under your notice.

First, I do not believe that he had botanical skill or experience adequate to name his vars. & species correctly; especially, as to distinguishing P. Jacquinii from Cowslip & umbellate Primrose.

Second— He states a result which no one else has hitherto shown; namely, that P. Jacquinii produced Primroses, & a Cowslip produced P. Jacquinii. That these (unusual, at least) results should both have come out at same time from single experiments, seems in the highest degree unlikely. I have tried P. Jacquinii for (I think) 16 descents and never got a primrose from it; nor has it ever sprung from seed of Cowslip or Primrose during 20 years of observation & experiment. I prefer to think either that he misnamed the plants, or mingled seed by some chance.

Third— He writes that in order “to prevent all errors as much as possible, I collected the seed myself, and again sowed it on beds, where no Primulæ had been previously grown”. He does not tell us whether these beds were near or wide apart, so that dew-worms &c. could not carry a seed from one to another. Nor does he show that any precaution was taken to prevent the seeds of Oxlips, primroses, cowslips (already in the garden) from being chance-mingled in the soil of those beds. The experimenter who thinks that “all errors as much as possible” are guarded against by the course he describes, must have very imperfect notion of the precautions which are necessary in such experiments. Had he been operating with exotic plants, never before grown in the garden, he might have assumed absence of seeds other than those purposely sown on his “beds”.

Fourthly— There are other instances, which show that Mr. S. is unreliable in his botanical statements; i.e. he hazards statements in print, which are not true; although I think from carelessness & imperfect knowledge, rather than mala fides (Phytol. III, p. 144— Cybele Brit. II p. 168.)5

It is for yourself to decide how far I am warranted in distrust on such grounds.

In the paper to which you refer,—Phytol. III, p. 703–5,—Mr Sidebotham says nothing about “artificial fertilization”. He simply writes, “to prevent any hybridization from the visits of insects, I protected them” (the oxlips, cowslips, primroses) “with glass during the early part of their flowering” (p. 704).

Cowslips, primroses, & polyanthuses are so usually grown, & have been so long grown in gardens, that we should never feel sure of their seeds not being in the ground, unless under some special cir˜ces. My own course has been, for particular experiments, to sow the seeds in flower pots, filled with mould from asparagus beds, or peat-earth dug where no Primula can be found. I dare not trust to the ordinary earth of the garden; for I see Primulæ spring up among potatoes, & other unlikely crops.

The asparagus beds, here very carefully kept weeded, & invariably forked over in spring, are extremely unlikely to have Primula seeds in them. Still, a chance seed might be brought to them on a tool, blown thither by wind, perhaps even come in the old horse-litter used as a manure dressing. Thus if I sowed primrose-seed in a flower-pot filled from an asparagus bed, & got 49 primroses & one cowslip, I should distrust my own experiment. But when I sow the seeds of an intermediate form in such soil, & find several primroses, several cowslips, & several intermediates, & look in vain for a primula on the Asparagus bed,—then I rely on the results. This result, I believe, is the only one that we can yet rely upon; namely, that an intermediate form can produce cowslips, primroses, & intermediates; vice versa cowslips & primroses can each produce the intermediates. As yet, distrust all else.6

I hope that some benefit was found from your stay at Torquay. I have just returned from a few weeks of indolence in the Isle of Wight, & the better for it.—

Believe me, always very truly | Hewett C. Watson

C. Darwin | Esqre


CD had apparently written to Watson inquiring about the reliability of Joseph Sidebotham’s experiments on Primula. Watson’s ‘intimation’ has not been traced, although he had criticised Sidebotham on a different topic, accusing him of making ‘mis-statements’ that he said were attributable to an ‘intellectual rather than moral deficiency’ (see Phytologist 3 (1848): 145).
Sidebotham 1847.
The editorial comment reads: ‘We have lately had an opportunity of observing seedlings produced in the second and third generation from Primula Jacquinii (Newm.) or Jacquin’s Primula, and find that they are in all respects identical with the parent plant. We again express a hope that the names of elatior and oxlip will not be applied to this species.’ Edward Newman was the general editor of the Phytologist, while George Luxford was the managing editor and a frequent contributor of articles (see Phytologist 1 (1844): v–vi).
See n. 4, above, and Watson 1847–59, 2: 168.
CD referred to Sidebotham’s work in the notes to his paper ‘On the two forms, or dimorphic condition, in the species of Primula, and on their remarkable sexual relations’, read before the Linnean Society of London on 21 November 1861 (Journal of the Proceedings of the Linnean Society (Botany) 6 (1862): 77–96; Collected papers 2: 45–63). Discussing the question whether the primrose (Primula vulgaris), the cowslip (P. veris), and the oxlip (P. elatior) were distinct species or only varieties of one species, CD stated his belief that oxlips were produced by cross-fertilisation between primroses and cowslips. In a note, he made reference to Sidebotham 1849 (Collected papers 2: 63 n. 6): Mr. Sidebotham (Phytologist, vol. iii. pp. 703–5) states that he protected his plants from crossing; but as he gives in detail all the precautions which he took, and says nothing about artificial fertilization, we may conclude that he did not fertilize his plants. As he raised very numerous seedlings, he would have had to fertilize many flowers, if they had been really well guarded against the visits of insects. Hence I conclude that his results are not worthy of trust.


Collected papers: The collected papers of Charles Darwin. Edited by Paul H. Barrett. 2 vols. Chicago and London: University of Chicago Press. 1977.

Sidebotham, Joseph. 1849. Experiments on the specific identity of the cowslip and primrose. Phytologist 3 (1848-9): 703–5. [Vols. 8,9]

Watson, Hewett Cottrell. 1847–59. Cybele Britannica; or British plants and their geographical relations. 4 vols. London: Longman.


The Primula experiments of J. Sidebotham; HCW’s distrust of the results [see J. Sidebotham, "Specific identity of the cowslip and the primrose", Phytologist 3 (1849): 703–5].

Letter details

Letter no.
Hewett Cottrell Watson
Charles Robert Darwin
Sent from
Thames Ditton
Source of text
DAR 181: 39
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 3258,” accessed on 21 September 2020,

Also published in The Correspondence of Charles Darwin, vol. 9