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Correspondence with Charles Darwin   159

appear in the forehead'. On going to the other litter, which I had never before got a proper view of, I found another young one with precisely similar marks. (The male parent was the same in both cases.) I have spent a most unsuccessful morning with new apparatus trying to inject more completely; but I have yet hopes of success by making some alterations.

I will return to you Naudin and the 2 pamphlets by to-morrow's book post. Very many thanks for them and for all the references. With great reluctande, I feel it would be too much for me to undertake the experiments. I am too ignorant 9f gardening, and, living in London with a summer tour in prospect, I don't see my way to a successful issue; but I hope to practise my eye and get some experience this year which may be of service next year or hereafter. I congratulate you about the Quagga taint. Once more about the rabbits, very many thanks for your hints, I will try more grey blood. Bartlett takes great interest and gives much care. Murie's assistant looks after the rabbits. Murie himself looks in now and then,

Very sincerely, F. GALTON.

Owing to the failure of Darwin's parallel letters we have no knowledge of what his hints were. The nature of the proposed plant-rearing experiments is equally unknown to us, but the suggestion may have remained in Galton's mind and have borne fruit in the sweet-pea experiments of a few years later. The Quagga taint' has close bearing on the present subject, for if a mother of breed A bore a child to a father of breed B, it seems likely that the 'gemmules' in the `circulation' of the unborn child might pass--into the mother's circulation and possibly affect a child born later to a father of her own breed A. The Quagga case, as indeed all instances up-to-date, of so-called telegony can now be dismissed from consideration. They depend essentially on (i) observation of variation within the pure breed not being sufficiently wide, or (ii) the assertions of kennel-men and others endeavouring to screen their responsibility for unplanned matings.

It is clear from this fifth letter that Galton was still hoping against the weight of accumulating facts for evidence that foreign 'gemmules' had been transfused with the blood.

(6)   5, BERTIE TERRACE, LEAMINGTON. April 8, 1870.

MY DEAR DARWIN, The white nose and vertical bar is, I find, of no importance. Bartlett was not accessible the day I found them out, but he has since told me they are common varieties, and I hear the same from Mr 13oyds, the rabbit-fancier and judge of poultry shows, from whom I bought them. Before leaving London last week I succeeded in infusing 2 per cent. of the rabbit's weight in alien blood, before I had only achieved 1.25 or 1/80th part which (on the supposition of Huxley that blood constitutes 1/10th of the whole weight of the body) is only 1/8th of the blood. In other words my transfusion, hitherto, has given only 1 great-grandparent of mongrel blood to the otherwise pure silver greys, and this is a very small matter. I do not like to risk another operation on the other jugular of my rabbits till after the forthcoming 3 litters, not till after I have had more success in the system of more abundant transfusion. I can do nothing with the blood in its natural state, it coagulates so quickly, so I defibrinise it. If I cannot ever succeed in transfusing as much into the rabbits as is necessary• to make a fair experiment, I must go to larger animals, and try cross-circulation with big dogs.

' Pencil note against this word : `white star'; Galton does not use the now common word flare.'

2 See Animals and Plants under Domestication, Vol. I, pp. 403-4, 1st Edn. Vol. I, p. 345, Ed. 1875. Darwin believed absolutely in telegony and attributes it to the "diffusion, retention and action of the gemmules included within the spermatozoa of the previous male." Animals and Plants, 1st Edn. Vol. ii, p. 388. Darwin's words seem to indicate that mere coition as apart from bearing offspring might produce telegony. The theory of telegony suggests that later born offspring should be more like the father than earlier born, but I have found no trace of this; see R. S. Proc. Vol. LX, pp. 273-83, 1896.