This year I never expected to be more than one in which to gain experience, for embryo grafting, as it has never been tried by anybody, cannot be learned about except by experiments. But as I am a young man yet, and hope to do a good deal of 'hammering,' I shall not let Pangenesis alone until I feel quite sure that it does not admit of being any further driven home by experimental work; and even if I never get positive results, I shall always continue to believe in the theory.
I am very sorry to hear that you 'much needed rest,' and do earnestly hope that you will not work too hard over the new edition of one of the most laborious treatises in our language—a treatise to which we always refer for every kind of information that we cannot find anywhere else.
Dunskaith: November 7.
I have to-day sent you a beautifully successful graft. It is of a red and white carrot, each bisected longitudinally, and two of the opposite halves joined. You will see that the union is very intimate, and that the originally red half has become wholly white. The graft was made about three months ago, at which time the carrots were very small, but the colours very decided. I think, therefore, that unless red carrots ever turn into white ones—which, I suppose, is absurd—the specimen I send is a graft-hybrid so far as the parts in contact are concerned. It will be of great importance, as you observed in your last letter, in a case like this, to see if the other parts are affected—i.e. to get the plant to seed if possible. This, I suppose, can only be done at this late season with so young a plant by putting it in a greenhouse. Perhaps, therefore, you might pot it, as soon as it arrives, and keep it till I go up. If you do not care, to take charge of it altogether, I can then get a home for it somewhere in the South. It will not require a deep pot, for I see that I have cut through the end of one of the roots. It would be as well, before potting, to cut off the end of the other root also, so that the one half may not grow longer than the other, and thus perhaps assert an undue amount of influence during the subsequent history of the hybrid. If the plant when you get it, or after potting, shows signs of drooping, I should suggest clipping off the older leaves to check evaporation: having found this a good plan with beets, &c.
In the same box with the hybrid there is another carrot. This is for comparison, it having been from the same seed and grafted (upon the crown) at the same time as the originally red half of the hybrid.
I am doubtful about the potatoes I sent. On looking over a number of 'red flukes,' I find some here and there are mottled. At any rate, I shall try other varieties next year, and not say anything about this doubtful case.
I forgot to say that the hybrid carrot is the only specimen of longitudinal grafting which I tried with carrots, having been somewhat disheartened with this method by the persistent way in which beets and mangolds refuse to blend when grafted longitudinally. There have thus been no failures with carrots grafted in this way.
If it is not too late, I may suggest that the passage in the 'Variation' about the deformity of the sternum in poultry had better be modified. I have this year tried some experiments upon Brahma chickens, and find that the deformity in question is caused by lazy habits of roosting—the constantly recurring pressure of the roost upon the cartilaginous sternum causing it to yield at the place where the pressure is exerted. The experiments consisted merely in confining some of a brood of young chickens in a place without any roost, and allowing the others to go about with all the March chickens. The former lot have the sternum quite straight, and the latter lot have it deeply notched.
I write to thank you for the copy of the new edition of the 'Variation' which I received a few days ago. I am very glad to see that you have thought my views about rudimentary organs worth a place, and that you speak so well of them.
The chapter on Pangenesis is admirable. The case is so strong, that it makes me more anxious than ever to get positive results in this year's experiments. I mean there seems less doubt than ever that such results must be obtainable if one hammers long enough. I did not know that there were so many cases of graft-hybridisation in potatoes. Perhaps it will be better this year to give one's main energies to other vegetables.