My dear William.—

I am very sorry to hear about your mare. I never knew what an unfortunate family we are in horse-flesh. It really is most provoking.—² Mamma orders me to compliment you on what a capital hand you have taken to write: it is very good. Aunt Susan was much pleased with your very nice note to her, which she sent on to us.—³

Now for business: Lythrum is a really wonderful case & will be worth an enormous amount of labour; & labour, by Jove, there will be, for I find I must castrate every flower. It will be a grand ending to my work on dimorphism.— The enclosed splendid diagram shows what I have hardly a doubt is the case: you must study it; the red lines show which pollen will fertilise which stigmas;⁴ all the other crosses I expect to be sterile or little fertile. In the long-styled (your long pistilled)⁵ the longer anthers are always yellow: has not this deceived you about maturity of flowers? Please let me hear.— I had overlooked difference in colour of filaments;— thanks.—

It w^d. be enormous advantage if you could have patience to gather at least 100 twigs & class them, & then I sh^d. give fact on your authority:⁶ employ the Boys;⁷ but caution them to gather only one twig from each plant.— I noticed slight difference in pollen of long & short stamens in the long-styled; & considerable difference between green & yellow pollen in the mid- & the short-styled plants. I wanted 3 good specimens. (not crushed with little damp, not wet, moss) to compare pollens: I suspect those that go in pairs in diagram are alike or nearly alike.—

I dare not trust specimens in my garden for some are monstrous. I also wanted specimens from same locality to get relative heights of stamens & pistils, & to put in spirits for Artist. You will not have time to do it; but if you could make me with camera in same position outlines of all six pollens, I would have them engraved from your outlines: these outlines would show whether there are three or more than three sizes & shapes. Pollen had better be dry; it sticks to glass I find; but whether when perpendicular I know not. But I do not think you will have time for the outlines.—⁸

If my diagram is the truth, is it not very curious & complex case? nothing like it, is known in whole organic world. See how well corresponding heights will carry pollen on proboscis from flower to flower. Do Humble or Hive-bees visit the flowers? ask George to see to this.—

Did you say that the other sp. of Lythrum grows with you?—Vaucher says it has only 2 forms;⁹ I am intensely curious to see them; & if you can I would get you in autumn to send me 3 or 4 plants of each kind.

GoodBye my dearest old man.— Lenny is going on very well.¹⁰ We are perplexed to death what to do. The Doctors urge in strongest terms to avoid all chance of infection; so did my Father in bad cases, & this has been very bad. All the children are now perfectly safe, if we can avoid future infection.—¹¹

C. Darwin

I think I have plants enough of Lythrum salicaria, but could you mark two of mid-styled.

Sunday Evening

P.S. I kept back my letter, because I received this morning the specimens.¹² They have been very useful: I return stamps. I am perplexed about pollen, & I believe I must measure all again distended by water: the breadth of dry grains seem to vary much from some cause.— Will you mark with string (3 strings for long-styled, 2 for mid & 1 for short-styled) 3 plants of Lythrum, as I much want a few pods, (wrapped up separately when ripe) to count seeds in each, to know natural product, & to compare shape of pods.—

George is a rare hand at watching insects¹³ & beg him to observe carefully what part of body of bee the knobbed stigma of long & mid-styled rubs against, when Bee sucking: no doubt the short anthers & stigma of short-styled rubs against the proboscis. After a Bee has visited several flowers of mid- & short-styled & long-styled flowers, it would be grand to catch him & kill him & see with lens whether one part of body did not abound with the green pollen & another part with yellow. Ask George to study my diagram & he will see what I mean; it is like the two pollens of Cowslip on proboscis of moth & Bees.

George ought to look out for Epipactis latifolia now in flower, & see what insects visit it.¹⁴ Good Night— Lenny sat in arm-chair for $\frac{1}{2}$ an hour.— Goodnight my three dear Boys.— | C. D.

I shall weary you about Lythrum.