Dear M^r Darwin

I have some recollection of intimating a distrust of M^r. Sidebotham’s recorded experiments on Primroses, &c. though I cannot now hit upon the intimation.—¹ However, I find his two papers in Phytol^st.   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 var^s. & 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 M^r. 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,—M^r 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