Telegony: Lord Morton's mare and the 'infection' of the dam by her first mate
A doctrine that the first male 'infects' the dam and leaves a trace in all her later offspring, even when the sire is a different male. Breeders accordingly guarded brood mares and bitches against chance matings.
The founding case was reported in 1821 by Lord George Morton: he put a nearly pure-bred Arabian mare to a quagga stallion, obtained a striped hybrid, and then sold the mare; by a black Arabian horse she bore two more foals, and in both Morton saw the stripes and mane of the quagga. The doctrine, in the words of the Scottish zoologist James Ewart, was shared by Agassiz, Darwin, Carpenter and Romanes, and Darwin in 1868 accepted Morton's case as 'perfectly well-ascertained'.
It had to be refuted by repeating the experiment outright: in the 1890s Ewart at Penycuik crossed mares with a Burchell's zebra and then with stallions of their own breed, and found no trace of the zebra in the later foals. Stripes occur in Arab horses without any quagga at all.
Why this date
The date follows the first publication. The Earl of Morton's letter to the President of the Royal Society was read in 1820 and printed in Philosophical Transactions, vol. 111 (1821), pp. 20-22 (checked against the article record on the Royal Society site). The belief itself, that the first sire 'corrupts' the female, is far older and goes back to antiquity, and the word 'telegony' was coined by Weismann in the 1890s; Morton's case is taken as the anchor because, in Ewart's words, the doctrine owed its nineteenth-century currency to it.
What grew out of it
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Pangenesis: gemmules from the whole body gather in the germ cells
influenced · Confidence: medium
Darwin accepted Morton's case as 'perfectly well-ascertained' and included the action of the first male on the dam among the facts pangenesis had to explain: gemmules of the quagga lodged in the mare's ovaries went on marking her offspring by other stallions.
Dispute: The main source here is Darwin himself rather than a historian: the words about the 'perfectly well-ascertained' case come from the chapter on pangenesis. Among historians, Burkhardt lists 'the influence of the male element on the female form' among the phenomena pangenesis was built to cover, and Ewart, who refuted telegony himself, testifies that Darwin held Morton's case to be strong evidence. No direct statement by a historian that pangenesis would have looked different without belief in telegony was found; the link is marked as influence, not as a prerequisite.
Link sources
- Charles Darwin, The Variation of Animals and Plants under Domestication, London: John Murray, 1868, vol. 2, ch. XXVII, p. 366 (Darwin Online, F877) (1868) Verified 20 Sep 2026
But we have the analogous and perfectly well-ascertained case of the male element of a distinct form, as with the quagga and Lord Morton's mare, affecting the ovarium of the female, so that the ovules and offspring subsequently produced by her when impregnated by other males are plainly affected and hybridised by the first male.
- Richard W. Burkhardt, Lamarck, Evolution, and the Inheritance of Acquired Characters, Genetics 194 (4), 793-805 (2013) Verified 20 Sep 2026
In his “provisional hypothesis of pangenesis,” he postulated that small, material particles that he called “gemmules” were produced in all the cells of the body, subsequently collected in the gonads and transmitted in reproduction, and accounted for a remarkable battery of hereditary and developmental phenomena, including (among others) reversion, “prepotency,” “the influence of the male element on the female form,”
- J. C. Ewart, «Telegony», Encyclopaedia Britannica, 11th ed., vol. 26 (1911) Verified 20 Sep 2026
Darwin and others having regarded Lord Morton’s mare as affording very strong evidence in support of the infection hypothesis, it was considered some years ago desirable to repeat Lord Morton’s experiment as accurately as possible.
"Verified" means that on that day the quotation was found at the address given, word for word. No date means we have not been able to open the source yet, not that the quotation is wrong.
- Charles Darwin, The Variation of Animals and Plants under Domestication, London: John Murray, 1868, vol. 2, ch. XXVII, p. 366 (Darwin Online, F877) (1868) Verified 20 Sep 2026
Other links
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Ewart's Penycuik experiments: Lord Morton's case repeated with a zebra
refuted by · Confidence: medium
Ewart repeated Morton's case with a zebra in place of the quagga, with control mares and several breeds, and found no trace of the zebra in any later foal; the same held for dogs and other animals. He concluded himself that 'the telegony tradition is not confirmed' by methodical experiment.
Dispute: The confidence is medium for two reasons. First, the strongest testimony is Ewart's own (the 1911 article), and the secondary sources are University of Edinburgh pages rather than a historian's work; the key historical paper, Burkhardt's 'Closing the Door on Lord Morton's Mare: The Rise and Fall of Telegony' (Studies in History of Biology 3, 1979, 1-21), is not available online and was not read. Second, the refutation was not instantaneous. In the 1899 book Ewart is still cautious and writes conditionally of 'should the fact of telegony be proved'; the unqualified conclusion appears by 1911, and the doctrine finally faded after 1900 together with the Mendelian explanation, under which stripes in Arab horses are reversion to ancestors, not a memory of the quagga. Separately: in 2014 Crean and colleagues described in the fly Telostylinus angusticollis an effect of the first male on offspring size through seminal fluid, which is called 'telegony' in a new sense; it has no bearing on the inheritance of the quagga's characters.
Link sources
- James Cossar Ewart (1851-1933), Our History, University of Edinburgh (2014) Verified 20 Sep 2026
To do this, Ewart repeated a classic experiment which supposedly proved this theory, the case involving the Arab mare belonging to Lord Morton which produced a striped foal after mating with a quagga, even when subsequently served by an Arab stallion. Ewart's experiment used a Burchell's zebra (the quagga having become extinct), but found that the 'subsequent foals' showed no signs of having been affected by a previous zebra sire. The results of his work were published in The Penycuik Experiments (1899).
- J. C. Ewart, «Telegony», Encyclopaedia Britannica, 11th ed., vol. 26 (1911) Verified 20 Sep 2026
Similar results having been obtained with horses and asses, there is no escape from the conclusion that the telegony tradition is not confirmed by such methodical investigations as were suggested some years ago by Professor Weismann (see Cossar Ewart, The Penycuik Experiments, 1899).
- Zebra Crossing: James Cossar Ewart, Romulus and the Penicuik Experiments, Towards Dolly (2013) Verified 20 Sep 2026
His most famous experiments were related to telegony, which is the theory, accepted at the time by most scientists and breeders, that ‘a previous sire may so “infect” the dam served by him as to impress certain of his characters upon her subsequent offspring by other sires.’ Ewart’s experiments with a variety of species; however, were uniformly negative.
"Verified" means that on that day the quotation was found at the address given, word for word. No date means we have not been able to open the source yet, not that the quotation is wrong.
- James Cossar Ewart (1851-1933), Our History, University of Edinburgh (2014) Verified 20 Sep 2026
Node sources
- Earl of Morton, A communication of a singular fact in natural history, Philosophical Transactions of the Royal Society of London 111, 20-22 (1821) Verified 25 Sep 2026
I subsequently parted with the seven-eighths Arabian mare to Sir Gore Ouseley, who has bred from her by a very fine black Arabian horse. I yesterday morning examined the produce, namely, a two-years old filly, and a year-old colt. They have the character of the Arabian breed as decidedly as can be expected, where fifteen-sixteenths of the blood are Arabian; and they are fine specimens of that breed; but both in their colour, and in the hair of their manes, they have a striking resemblance to the quagga.
- J. C. Ewart, «Telegony», Encyclopaedia Britannica, 11th ed., vol. 26 (1911) Verified 20 Sep 2026
The prevalence of the belief in telegony at the present day is largely due to a case of supposed infection reported to the Royal Society in 1820 by Lord Morton.
- J. C. Ewart, «Telegony», Encyclopaedia Britannica, 11th ed., vol. 26 (1911) Verified 20 Sep 2026
It is noteworthy that L. Agassiz, C. Darwin, W. B. Carpenter, and G. J. Romanes were all more or less firm believers in the doctrine of infection, and that a few years ago, with the exception of Professor A. Weismann, all the leading biologists had either subscribed to the telegony doctrine or admitted that “infection of the germ” was well within the bounds of possibilities.
- Charles Darwin, The Variation of Animals and Plants under Domestication, London: John Murray, 1868, vol. 2, p. 366 (Darwin Online, F877) (1868) Verified 20 Sep 2026
But we have the analogous and perfectly well-ascertained case of the male element of a distinct form, as with the quagga and Lord Morton's mare, affecting the ovarium of the female, so that the ovules and offspring subsequently produced by her when impregnated by other males are plainly affected and hybridised by the first male.
"Verified" means that on that day the quotation was found at the address given, word for word. No date means we have not been able to open the source yet, not that the quotation is wrong.