study of the embryology of the horse, about which, owing to the
costliness of the necessary investigations, very little is at present
known. At the same time he determined to inquire into certain theories
of heredity which have for centuries influenced the breeders of horses
and cattle, and the belief in which has played a large part in the
production of our more highly bred domestic animals. Foremost amongst
these is the view widely held amongst breeders that a sire influences
all the later progeny of a dam which has once produced a foal to him.
This belief in the ‘infection of the germ,’ or ‘throwing-back’ to a
previous sire, is probably an old one, possibly as old as the similar
faith in maternal impressions which led Jacob to placed peeled wands
before the cattle and sheep of his father-in-law Laban. The phenomenon
has recently been endowed with a new name--Telegony. Since the
publication of Lord Morton’s letter to Dr. W. H. Wollaston, President of
the Royal Society, in 1820, it has attracted the attention, not only of
practical breeders, but of theoretical men of science. The supporters of
telegony, when pressed by opponents, having almost always fallen back on
Lord Morton’s mare, it will be well to recall the chief incidents in the
history of this classic animal.
It appears that early in last century Lord Morton was desirous of
domesticating the quagga. He succeeded in obtaining a male, but, failing
to procure a female, he put him to a young chestnut mare of
seven-eighths Arab blood which had never been bred from before. The
result was the production of a female hybrid apparently intermediate in
character between the sire and the dam. A short time afterwards Lord
Morton sold his mare to Sir Gore Ouseley, who bred from her by a fine
black Arabian horse. The offspring of this union, examined by Lord
Morton, were a two-year-old filly and a year-old colt. He describes them
as having
‘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.’
The description of the stripes visible on their coats is careful and
circumstantial, but the evidence of the nature of the mane is less
convincing:
‘Both their manes are black; that of the filly is short, stiff, and
stands upright, and Sir Gore Ouseley’s stud-groom alleged that it
never was otherwise. That of the colt is long, but so stiff as to
arch upwards and to hang clear of the sides of the neck, in which
circumstance it resembles that of the hybrid.
This is the classical--we might almost say the test--case of telegony:
the offspring resembled not so much the sire as an earlier mate of the
dam. The facts related tended to confirm the popular view, and that view
is now widely spread. Arab breeders act on the belief, and it is so
strongly implanted in the minds of certain English breeders that they
make a point of mating their mares first with stallions having a good
pedigree, so that their subsequent progeny may benefit by his influence,
even though poorly-bred sires are subsequently resorted to.
The evidence of Lord Morton’s mare convinced Darwin of the existence of
telegony. After a careful review of the case, he says: ‘There can be no
doubt that the quagga affected the character of the offspring
subsequently got by the black Arabian horse.’ Darwin, however, latterly
came to the conclusion that telegony only occurred rarely, and some
years before his death expressed the opinion that it was ‘a very
occasional phenomenon.’ Agassiz believed in telegony. He was strongly of
opinion
‘that the act of fecundation is not an act which is limited in its
effect, but that it is an act which affects the whole system, the
sexual system especially; and in the sexual system the ovary to be
impregnated hereafter is so modified by the first act that later
impregnations do not efface that first impression.
Romanes also believed that telegony occasionally occurred. He paid a
good deal of attention to the matter, commenced experiments in the hope
of settling the question, and corresponded at length on this subject
with professional and amateur breeders and fanciers. The result of his
investigations led him to the conclusion ‘that the phenomenon is of much
less frequent occurrence than is generally supposed. Indeed, it is so
rare that I doubt whether it takes place in more than 1 or 2 per cent.
of cases.’ He adds that his professional correspondents regard this as
an absurdly low estimate. Tegetmeier and Sutherland believe that
telegony exists in dogs and other animals; and Captain Hayes, whose
opinion probably coincides with that of the majority of veterinary
surgeons, takes for granted that it occurs in horses. A controversy some
years ago in the _Contemporary Review_ shows us that Mr. Herbert Spencer
was a firm upholder of telegony, and that he had a theory of his own as
to the mode in which it is brought about.
The explanations put forward by the supporters of telegony as to the
mechanism by which it is effected differ widely. It will be well to
discuss them here. The view that telegony is due to the mental
impression of the dam, held by Sir Everard Home and many others since
his day, has nothing to support it; but the other two views, which may
be termed (1) the infection hypothesis, and (2) the saturation
hypothesis, demand more detailed treatment.
The infection hypothesis supposes that the reproductive organs of the
mother are specifically altered or infected by bearing offspring to a
previous sire. The method by which this is effected is now most commonly
thought to be by a fusion or blending of some of the unused germ-cells
of the first sire with the unripe ova in the ovary of the dam.
Physiologists, however, regard this as very unlikely. Although at the
time that the ovum of a mare is fertilized there are usually other ova
almost mature, or approaching maturity, these disappear during
gestation. Subsequent offspring arise from successive crops of ova, into
whose composition it is most improbable that the earlier spermatozoa
could enter. Further, it is known that in the Equidæ the male germinal
cells do not live long within the body of the female; they are already
disintegrating eight days after insemination, and they probably lose
their fertilizing power after three or four days, if not sooner; hence
it is not possible for them to remain in the body during the whole of a
period of gestation and to fertilize the next succeeding batch of ova.
The second theory which attempts to account for the phenomenon of
telegony is termed the saturation hypothesis. In the words of Mr. Bruce
Lowe, who has formulated the theory, we may say that, ‘briefly put, it
means that with each mating and bearing the dam absorbs some of the
nature or actual circulation of the yet unborn foal, until she
eventually becomes saturated with the sire’s nature or blood, as the
case may be.’ Although not very well expressed, it is obvious what the
author means; and if this saturation really takes place, it accounts for
a good deal more than telegony. It would affect the whole body and
nature of the dam, and not only the reproductive organs, which,
according to Romanes and others, are alone influenced. There is no doubt
that matter can and does pass from the blood of the embryo into that of
the mother--in certain classes of mammalia, at any rate. The published
Report of the Fourth International Congress of Zoology, which met in
1898 at Cambridge, contains a paper by Professor Hubrecht, of Utrecht,
in which he describes certain blood-corpuscles formed in the embryo
which undoubtedly make their way into the maternal bloodvessels and take
part in her circulation. That matter can pass from the bloodvessels of
the embryo to those of the mother is further demonstrated by the
experiments of M. Charrin, who showed that diphtheritic toxins injected
into the embryos of a rabbit caused the death of the mother within five
days, and further that a rabbit can be rendered immune by injecting
anti-diphtheritic toxins into the embryos.
There is nothing in these experiments to show that the nature of the dam
is radically altered; and in the Equidæ, in which, as we have seen, the
classical case of telegony occurred, there is a strong presumption
against any such transference of blood-corpuscles from the embryo to the
mother. Still, taking all the facts into consideration, it appears that,
if telegony exists, it is more likely to be brought about by saturation
than by the direct infection of the ovary; though, if the former method
be accepted, telegony must be confined to the mammals and the
comparatively few other animals whose young spend some time in the body
of the mother and are not hatched out from eggs which have lost their
connexion with the body of the mother at an early stage.
Before passing on to consider the views of those who hold that telegony
does not exist and to see what light the Penycuik experiments throw on
the subject, a word or two may be said about Mr. Herbert Spencer’s
theory of the mode in which telegony, in which he firmly believed, is
brought about. He suggested that some ‘germ-plasm’ passes from the
embryo into the mother and becomes a permanent part of her body, and
that this is diffused throughout her whole structure until it affects,
amongst other organs, the reproductive glands. This view, which in some
respects recalls the pangenesis of Darwin, is intermediate between the
saturation and the infection hypotheses. Professor Ewart refers to it as
‘indirect infection.’
Weismann, to whom we owe the term telegony, came to consider the facts
for and against its existence in connexion with his well-known inquiry
into the inheritance of acquired characters. If telegony be true, there
is no need to look further for a clear case of the inheritance of a
character which has been acquired during the lifetime of the parent. The
quagga-ness--if one may be permitted to use such an expression--of Lord
Morton’s mare was acquired when she was put to the quagga or shortly
afterwards, and was transmitted to her foals. A clearer case of a
character acquired during lifetime and transmitted to offspring could
not be imagined. Weismann does not absolutely deny the possibility of
the existence of telegony, but he would like more evidence. In the
_Contemporary Review_ he writes: ‘I must say that to this day, and in
spite of the additional cases brought forward by Spencer and Romanes, I
do not consider that telegony has been proved.’ And further: ‘I should
accept a case like that of Lord Morton’s mare as satisfactory evidence
if it were quite certainly beyond doubt. But that is by no means the
case, as Settegast has abundantly proved.’ He would, in fact, refer the
case to reversion, and quotes Settegast to the effect that every
horse-breeder is well aware that the cases are not rare when colts are
born with stripes which recall the markings of a quagga or zebra. We
shall return to this point later.
A considerable number of German breeders support the contention of
Weismann that telegony is as yet unproven, and it may be pointed out
that in Germany, on the whole, breeders have had a more scientific
education than in England, and that in that country science is regarded
with less aversion or contempt than is usually the case among so-called
practical men in England. Settegast has been quoted above: neither he
nor Nathusius, a leading authority on domestic cattle, has ever met with
a case of telegony, and the same is true of Professor Kühn, the late
Director of the Prussian Agricultural Station at Halle. We may mention
one more case of an experienced breeder who was equally sceptical--the
late Sir Everett Millais, who was, as is well known, an authority of
great weight in the matter of dog-breeding. He writes as follows, in a
lecture entitled ‘Two Problems of Reproduction’:
‘I may further adduce the fact that in a breeding experience of
nearly thirty years’ standing, during which I have made all sorts
of experiments with pure-bred dams and wild sires, and returned
them afterwards to pure sires of their own breeds, I have never
seen a case of telegony, nor has my breeding-stock suffered. I may
further adduce the fact that I have made over fifty experiments for
Professor Romanes to induce a case of telegony in a variety of
animals--dogs, ducks, hens, pigeons, etc.--but I have hopelessly
failed, as has every single experimenter who has tried to produce
the phenomenon.’
It is thus evident that there was a considerable body of opinion, both
practical and theoretical, for and against telegony; and that a
re-investigation of the subject was urgently needed. Such a
re-investigation has been begun by Professor Ewart at Penycuik. Since
the clearest and most definite evidence of this throwing back to a
previous sire is derived from the crossing of different species of the
Equidæ, it was desirable to repeat the experiment of Lord Morton. This
is now unfortunately impossible, because the quagga is extinct. The
zebra is, however, still with us, and the mating of a zebra stallion
with every variety of horse, pony, and ass, and subsequently putting the
dam to pure-bred sires, has been the more important part of the numerous
experiments carried on in the Midlothian village some ten miles
southwest of Edinburgh.
Before considering in detail the result of the experiments it will be
necessary to say a few words on the question of the various species of
zebra; and since, like Weismann, Professor Ewart explains certain of the
phenomena attributed to telegony by reversion, it will be as well to
inquire how far reversion is known amongst the Equidæ, and what evidence
we have that the ancestor of the horse was striped.
Matopo, the zebra stallion from which Professor Ewart had, some eight
years ago, bred eleven zebra-hybrids from mares of various breeds and
sizes, belongs to the widely distributed group of Burchell’s zebras.
Many sub-species or varieties are included in this group, which, as
regards the pattern of the stripes, passes--in certain varieties found
in Nyassaland--into the second species, the mountain zebra, once common
in South Africa. The third species is the Grévy’s zebra of Shoa and
Somaliland; it is probably this species which attracted so much
attention in the Roman amphitheatres during the third century of our
era. A pair of Somali zebras were presented to the late Queen some years
ago by the Emperor Menelik, and for a time were lodged in the Zoological
Gardens, Regent’s Park. This species measures about fifteen hands high,
is profusely striped, and stands well apart from the other two groups.
It is important to note that in Professor Ewart’s opinion it is the
most primitive of all the existing striped horses.
There is no direct evidence that the ancestors of horses were striped.
Certain observers think that some of the scratches on the life-like
etchings on bone, left us by our palæolithic cave-dwelling ancestors,
indicate such stripes; but little reliance can be placed on this. On the
other hand there is much indirect evidence. Every one who has an eye for
a horse, and who has travelled in Norway, is sure to have noticed the
stripings, often quite conspicuous, on the dun-coloured Norwegian
ponies. Colonel Poole assured Darwin that the Kathiawar horses had
frequently ‘stripes on the cheeks and sides of the nose.’ Breeders are
well aware that foals are often born with stripes, usually on the
shoulders or legs, less frequently on the face. Such stripes as a rule
disappear as the colt grows up, but can often be detected in later life
for a short time after the coat has been shed; they are sometimes only
visible in certain lights, and then produce somewhat the same impression
as a watered silk. From the facts that more or less striped horses are
found all over the Old World; that in Mexico and other parts of America
the descendants of horses which were introduced by the Spaniards and
which afterwards ran wild are frequently dun-coloured and show stripes;
that foals are frequently striped; and that mules not uncommonly have
leg and shoulder stripes, the inference is largely justified that the
ancestors of all our horses were striped.
The hypothesis of reversion has recently been called in question, and no
doubt the term has been much abused. Animals and plants have been said
to revert to some remote ancestor when they have varied in some
particular, and this variation has then been described as a primitive
character possessed by the ancestor; thus there has been much arguing
in and about a vicious circle. But the fact that a term has been
illogically applied does not destroy the existence of that which the
term signifies, and there can be no doubt that reversion exists. That it
exists in the Equidæ is shown by the following proofs: (1) The ancestors
of the horse had four premolar teeth in the upper jaw; the modern horse
has lost, or is losing, the first of these, and as a rule has only
three. When the first is present--the so-called wolf-tooth--it is small,
and soon disappears. Zebras usually retain the ancestral number. A few
years ago Professor Ewart had a Shetland pony in which the first
premolar was relatively nearly as large as it is in hipparion, one of
the supposed ancestors of the horse. (2) There is no doubt that the
horse is descended through three-toed ancestors from five-toed
ancestors. All trace of the latter condition is now lost in development,
but an embryo horse six weeks old has three toes as completely formed as
those of a rhinoceros. The outer toes then begin to dwindle, and the
newly-born foal supports itself on its central digit alone; but horses
are occasionally born with two digits, each encased in a hoof, and at
very rare intervals with three. Cæsar’s favourite horse was
polydactylous, and so was Alexander’s Bucephalus. Major Waddell, in his
book on the Himalayas, refers to a creamy fawn-coloured pony, which ‘had
a black stripe down the spine ... broad black stripes over the
shoulders, flanks, and legs, and dappled spots over the haunches.’ Many
other instances might be quoted, but enough has been said to show that
reversion is found in the Equidæ, as in other families of animals.
We now pass to the experiments made at Penycuik in crossing the zebra
Matopo with various mares of different breeds.
1. Matopo was first mated with Mulatto, one of Lord
[Illustration: MATOPO.
_To face page 84._]
Arthur Cecil’s black West Highland ponies. The result was the hybrid
Romulus, which on the whole, both in mental disposition and bodily form,
took more after his father than his mother. His striping was even more
marked than that of his sire. He had a semi-erect mane, which was shed
annually. The pattern of the markings, on both body and face, resemble
the stripes on a Somali zebra--which, as we have seen, is regarded by
Professor Ewart as the most primitive type--more than they resembled
that of any of Burchell’s zebras. The profuse striping is a point of
difference between this hybrid and Lord Morton’s. The quagga-hybrid was
less striped than many dun-coloured horses (see illustration).
The mother Mulatto was next mated with a highly-bred grey Arab horse,
Benazrek. The offspring agreed in all respects with ordinary foals; it
had, however, a certain number of indistinct stripes which could only be
detected in certain lights. The stripes were not nearly so clear as in a
foal bred by Mr. Darwin from a cross-bred bay mare and a thoroughbred
horse, and they disappeared entirely in about five months.
Mulatto has produced a third foal to Loch Corrie, a sire belonging to
the Isle of Rum group of West Highland ponies, and closely resembling
its mate. This foal was about as much striped as its immediate
predecessor. In both cases the pattern of the stripe differed not only
from that of Matopo, the previous sire, but from that of the hybrid
Romulus. These two foals seem to lend some support to telegony; but the
evidence which might be drawn from the second of them is destroyed by
the fact that the sire, Loch Corrie, has produced foals from two West
Highland mares, one brown and one black, and each of these foals has as
many and as well-marked stripes as the foal of Mulatto.
2. Four attempts were made to cross the zebra with Shetland ponies: only
one succeeded. The hybrid was a smaller edition of Romulus. The dam Nora
had been bred from before, and had produced by a black Shetland pony a
foal of a dun colour which was markedly striped. After the birth of the
hybrid she was put to a bay Welsh pony; the resulting foal had only the
faintest indication of stripes, which soon disappeared. It is a
remarkable fact that Nora’s foals were more striped before she had been
mated with the zebra than afterwards.
3. Five Iceland ponies were mated with Matopo, of whom one produced, in
1897, a dark-coloured hybrid. The dam, Tundra, was a yellow and white
skewbald, which had previously produced a light bay foal to a stallion
of its own breed. Her third foal (1898) was fathered by a bay Shetland
pony, and in coloration closely resembled its dam. There was no hint of
infection in this case. In 1899 Professor Ewart bred from this mare, by
Matopo, a zebra-hybrid of a creamy fawn colour, and so primitive in its
markings that he believes it to stand in much the same relation to
horses, zebras, and asses as the blue-rock does to the various breeds of
pigeons (see illustration).
4. Two Irish mares, both bays, produced hybrids by Matopo, and
subsequently bore pure-bred foals. One of the latter was by a
thoroughbred horse, the other by a hackney pony. The foals were without
stripes, and showed no kind of indication that their mother had ever
been mated with a zebra.
5. Although Professor Ewart experimented with seven English thoroughbred
mares and an Arab, he only succeeded in one case. The mare produced twin
hybrids, one of which, unfortunately, died immediately after birth. In
the summer of 1899 the same mare produced a foal to a thoroughbred
chestnut; ‘neither
[Illustration: TUNDRA (AN ICELAND PONY), HER FOAL, CIRCUS GIRL (BORN
1898), AND HER HYBRID-FOAL, SIR JOHN (BY MATOPO), WHEN A MONTH OLD (BORN
1899).
_To face page 86._]
in make, colour, nor action’ does it in any way resemble a zebra or a
zebra-hybrid.
6. A bay mare which had been in foal to Matopo for some months
miscarried. Here--if there is anything in the direct infection
theory--the unused germ-cells of the zebra had a better chance than
usual of reaching the ova from which future offspring are to arise, yet
neither of the two foals which this mare subsequently produced to a
thoroughbred horse ‘in any way suggests a zebra.’
The above is the record of the successful experiments which have been
tried at Penycuik, with a view of throwing light on the existence of
telegony in the Equidæ. Experiments have also been made with other
animals, such as rabbits, dogs, pigeons, fowls, and ducks. Space allows
us to quote but one. Six white doe rabbits, all of which had borne pure
white offspring to white bucks, were crossed with wild brown rabbits.
The result was forty-two young rabbits, all of a bluish-black colour,
which in a very short time turned to a brown. These, at the time of
writing, were about half grown, and Professor Ewart tells us that it was
almost impossible to distinguish them from a full-blooded wild rabbit
kept in the same enclosure. The half-breeds, however, were tamer and
slightly lighter in colour. The mother does next bred with white bucks
again, and in every case bred true. The pure white young showed no trace
of throwing back to a previous sire.
A phenomenon somewhat similar to telegony, and one which seems at
present quite unexplained, is that a hen which has been crossed with a
cock of another breed often lays eggs whose shell is no longer like that
of its own breed, but in colour, and frequently in texture, resembles
that of the breed with which it has been crossed. Mr. Bulman has
recorded a case of this in the pages of ‘Natural Science.’ Some
Orpington fowls which laid eggs of a buff tint were allowed to run
loose in a large yard with fowls of various breeds. After a few months
they were confined in separate pens again, and for several weeks
afterwards they continued to lay white eggs. There seems to be no doubt
of the existence of this curious phenomenon; it is mentioned by Gadow in
his volume on ‘Birds,’ in Bronn’s ‘Thierreich,’ by Nathusius in the
_Journal für Ornithologie_, and in Newton’s ‘Dictionary of Birds.’ When
one calls to mind that the shell is deposited by a special shell-gland
which is in no way connected with the ovary, but is a part of the quite
distinct oviduct, and that the change in the colour of the eggshell must
be caused by some change brought about in this gland by
cross-fertilization, we begin to recognize how mysterious and
inexplicable are many of the problems which affect breeding.