To T. H. Huxley 29 [September 1855]1
Down Farnborough Kent
My dear Huxley
Your letter, as you may well suppose, has greatly interested me.2 Let me premise that I have often groaned over my want of elementary knowledge in microscopical structure, so that I could not recognise an incipient ovum. I could only make out, that at certain times in the gut-formed gland (after spirits) there were aggregations of matter in colour & aspect like the contents of the ovarian tubes.3 I cannot understand yet that I could have fancied that I saw what I call “pointed little balls with a large inner cell & this again with 2 or 3 included granules.”4 But do not think that I have the presumption to dispute what you say about the contents of the gut-formed glands.5 I could only ask whether you have examined specimens taken at very different periods: I remember well what a diversity of appearance these glands presented. Have you seen see P.S. them nearly empty with the walls studded with cells? Have you seen the pellets of yellow (after spirits) cellular matter apparently travelling down the ducts: these were so conspicuous, (though very rarely met with) that really I think no amount of blundering could have made me fancy them; for I removed the duct.— By the way I shd. have said that you give a perfectly correct account of what my idea was.—
Whatever the nature of the gut-formed glands may be; I cannot doubt from the many cases which I have seen, that you will find that the ovarian tubes with ova are directly continuous with them or rather with the duct leading from them:6 I remember one case of Conia (= Tetraclita), in which I laid them so open that Leonard the artist,7 drew them for me. On the other hand I cannot persuade myself for a second that they are cement-glands; though it is very certain (for I have seen it repeatedly) that in the pupal condition the cement-ducts run from the antennæ to these glands;8 on the other hand the branching out of this duct in the middle into the ovarian tubes in the very young cirripede seemed to me equally plain. That they are not cement glands, I must conclude from all my observations on the complicated apparatus in all the sessile cirripedes; in which at each period of growth new glands could be seen in process of formation.9
Again I really traced the cement duct in Conchoderma into the gland figured, Pl. IX fig 310 as plainly as the aorta into the heart.— Though I found the gland & dissected it out of the body in Conchoderma, Pollicipes, Scalpellum & Ibla, I never found it in Lepas; & I remember feeling considerable surprise at this: I will write no more; but I cannot conceive that I can have erred in (1st) so repeatedly tracing the branching ovarian tubes into the duct close to the gut-formed glands & (2d) & more especially in tracing the cement duct into the cement-gland.— If these points are false, I shall never trust myself again.11 That the gut-formed gland has some other relation to the ovarian tubes than what I imagined seems to follow from what you have seen;12 but I supplicate you to look at a few more full-grown specimens; but I wish it was not autumn.— The white deep-water ribbed Bal. porcatus you would find a good species.
Forgive the length of this letter. If you work at all more at cirripedes, do attend to circulatory system; it was quite beyond my tether.13 The open space under the skin between the scuta (ie on the ventral surface homologically!) seemed to me the great centre, & there are some desperately odd voluntary small superficial muscles looped one into other.—
Thank you much for writing to me. I have really no suggestions to offer, but I am delighted to hear how energetically you seem to be at work. I hope that your marriage will not make you idle: happiness, I fear is not good for work.
My dear Huxley | Most truly yours | C. Darwin
P.S. I have just remembered that I had one specimen preserved between glass. This I have just examined and broken up; it is in the state which I call “more or less globular or finger-shaped aggregations of pulpy matter”.14 But I can assure you I have often seen these organs presenting a wholly different appearance with cells. I could not in this specimen detect a single cell with included Nuclei or granules (or whatever, they might be called) and which I compared with drawings by (I think) Steenstrup15 and which appeared to my ignorant eyes exactly like ovigerms. When you have seen this organ in 2 or 3 different states, and say that positively in none could ovigerms be in formation, I will give up the ghost handsomely and entirely like a gentleman.
Responds to THH’s questioning of his observations on cirripede anatomy with extensive discussion of what he observed. Admits his elementary knowledge of microscopical structures but seriously doubts he has erred. Cement glands, ovarian tubes, etc.
Please cite as
Darwin Correspondence Project, “Letter no. 1757,” accessed on 4 December 2016, http://www.darwinproject.ac.uk/DCP-LETT-1757