Russel Wallace : Alfred Russell Wallace (sic)
Dr Montague R. Leverson, of Fort Hamilton, New York, having written me about the facts as to the young Cuckoo throwing the other young birds out of the nest of its foster-parents, which account he, like so many other persons, wholly disbelieves, I have recently obtained for him Mrs Blackburn's book, "Birds of Moidart," (1895) in which she describes her careful and repeated observation of the fact, and gives a drawing of the bird in the very act of performing the operation. The same description was first published in Nature, vol. v., p. 383, signed J. B., but referring to a versified tale, "The Pipits," illustrated by Mrs Hugh Blackburn, (1872, Maclehose, Glasgow). The same letter was printed in The Lancet in 1892 (July 2nd).
As the observation now made is most precise and direct, and as it curiously agrees in details with the observations of Jenner in his letter to John Hunter, printed in the Philosophical Transactions (vol. lvii-viii, pp. 225, 226) it is, I think, due to themselves, and to our cause, that those writers who have adduced Jenner's statements on this point as a proof of his unreliability should acknowledge their error, in order that this accusation, unsupported by observation or by any well established facts, should not continue to be brought forward as an argument by anti-vaccinators.
This is the more important as the facts had already been several times confirmed by independent testimony, so as to satisfy some of our most careful and accurate naturalists. In the 4th edition of Yarrell's British Birds, edited by Prof. Alfred Newton, he says, after quoting Jenner's account,--"This remarkable habit of the young Cuckoo has been so abundantly confirmed by the testimony of unimpeachable eye-witnesses in many countries, and in England among others by Montague and Mr Blackwall, whose names are a sufficient guarantee for the accuracy of their observations, that the unbelief in Jenner's statements, hinted or openly expressed by some zoologists, is hardly to be justified by the most ardent supporter of absolute proof." (vol. ii., p. 396.)
Prof. Newton also tells us that a French writer, Lottinger, in 1782, "himself had personal proof of the expulsion of an egg from the nest by a young Cuckow, (Hist. du Coucou d'Europe, p. 18.)" And in the English Cyclopædia (Natural History), vol. ii., p. 246, there is an account of an observation earlier than that of Jenner giving almost exactly the same facts.
And all we have against these repeated and concordant observations is--not observation to the contrary, but more or less positive denial, disbelief, or mere ridicule. Among these unbelievers Waterton has been quoted, as if his opinion should outweigh other observers' facts. But there was probably no more prejudiced or irrational writer in the English language when dealing with the observations of others. To give two examples; he denied the possibility of the Dipper walking under water, and tried to prove it by reasoning and ridicule. Yet no fact in nature is more certain or more universally admitted by ornithologists. In the same way he tried to prove that Vultures found their food by smell and not by sight, ridiculing the direct observations and experiments of Audubon and others which were opposed to his views. Yet here again the unanimous verdict of naturalists is against him, and, as regards the very same species which he observed in Guiana, I, myself, proved that it does not detect food by smell. (See my Travels on the Amazon, cheap edition, p. 125).
I should have written to make this correction and appeal in favour of Jenner long ago, but, till recently, I had no knowledge of Mrs Blackburn's work, and could give no reference to it. Having now read her account and examined her drawing, I need only say, in conclusion, that I am completely satisfied of the accuracy of Jenner's observation thus fully and repeatedly confirmed.
Alfred R. Wallace.