THE INFLUENCE OF A PREVIOUS SIRE. By A. L. BELL, M.D., Dunfermline. FOR generations past it has been believed and tacitly acknow- ledged by many honest observers that the progeny of one sire may be influenced in colour, formation, or other outstanding characteristic by a previous sire by which the mother has pro- duced offspring, until, at the present day, it constitutes one of the fundamental beliefs that such is actually the case. For example, it is firmly believed by veterinarians and horse-breeders generally that if a thoroughbred mare have a foal by a work- horse or a stallion of a different breed from herself, she is spoiled for ever for breeding purposes, because, even to a thoroughbred stallion she will produce foals with a trace of impurity derived from the alien sire of her previous foal. There are several well- known cases often quoted in support of this belief. In the often quoted case recorded by Lord Morton, a seven-parts bred chest- nut mare was served by a Quagga, the result being a hybrid foal resembling the Quagga, especially in having stripes on the body, this being only what was to be expected from the way in which the foal was bred. Next year, and two following years as well, the same mare was put to a black Arabian stallion, and the foals by this sire also showed traces of the Quagga " in the possession of body stripes and bars on the legs." 1 It seems strange that in this instance the bars on the legs should be referred to the influence of the Quagga, seeing that the Quagga, though striped on the body, has no leg-stripes, as the Zebra has. In a second case, that of "Greyfriar," a race-horse got by " Hermit," a thoroughbred, out of " Perseverance," also a thoroughbred, his grey colour is said to have been due to the influence of a grey horse by which Greyfriar's dam had produced a foal the year before. But as Perseverance was herself a grey, having thrown back a long way to a grey ancestor, the case may be dismissed as valueless in reference to this subject. 1 PhilosophicZ Transactions, 1821, page 20. Darwin's Origin of Species, chap. v. page 129. 260 DR A. L. BELL. There are many other instances, more or less marked and recorded, with more or less conciseness and detail. For instance, M'Gillivray reports a case quoted by Dr Alexander Harvey in the Aberdeen Journal, of 28th March 1849, as follows: " A mare belonging to Sir Gore Ouseley was covered by a Zebra and gave birth to a hybrid. The year following, the same mare was covered by a thoroughbred stallion, and next year by another horse. Both the foals thus produced were striped, i.e., partook of the characters of the Zebra." This is, in all probability, the case of Lord Morton's chestnut Arab mare, which became the property of Sir Gore Ouseley after bearing a foal to a Quagga.1 However that may be, the case is described in a slip-shod fashion; no account of the mare's breeding is given by M'Gillivray; and there is another objection, to which I shall refer in criticizing Lord Morton's case. In a case referred to by Dr Harvey, a healthy woman was twice married; her first husband was scrofulous, as were her children. The second husband was perfectly healthy, and, so far as was known, had no trace of scrofula, yet the children born to him by the widow of the scrofulous husband were tainted dis- tinctly with scrofula; and it is explained that the first husband not only tainted his own children, but impressed his taint on subsequent offspring not his own. But it is more probable, in this case, that the scrofula was a form of syphilis, or, as Harvey himself says, " the wife may have imbibed the virus in a latent form, and subsequently contaminated the children of the second husband." 2 Harvey quotes also a case which was reported to him from the Island of Grenada, where certain ewes, themselves white and woolly, were served by a ram of a chocolate colour and having a hairy or coarse fleece. The year following they were served by a ram of their own breed, "but the progeny showed distinct marks of resemblance to the first sire." Besides the imperfect description of the " marks of resemblance," and the absence of any details as to the pedigree of the ewes, it is not made clear that the ewes were guarded from the intrusions of the " chocolate coloured ram" during the second breeding season. It is well 1 See Philosopjhical Transactions, 1821, page 20. 2 Monthly Journal of Medical Science, September 1849, p. 1136. THE INFLUENCE OF A PREVIOUS SIRE. 261 known to sheep-breeders that rams will travel long distances to fulfil their destiny with ewes in season. There is yet another case which I have seen put down and heard related, but cannot tell who is the author. I refer to the instance of a white woman whose first husband was a negro, and who afterwards married a white man. She bore children to both husbands, and it is stated that the children of her second husband possessed negro characteristics due to the influence of the first husband. To account for the influence of a previous sire, there are two theories put forward. First, that the spermatozoa of the first sire pass up the Fallopian Tubes to the ovaries and are absorbed by the unripe ova contained therein; and that these sperms, though of insufficient power to fertilize the unripe ovum, have yet sufficient power to alter the development of that ovum subsequently when it is fertilized by the spermatozoa of the second sire. I think it is admitted that the life of the sperma- tozoa is limited to a few hours or days at the longest, and that their powers of fertilizing exist only during their life. When a spermatozoon is absorbed into an unripe ovum, it must surely die, so far as its individual existence is concerned, by becoming part of the ovum. It seems to me incredible that a dead sperm can exert any influence on the development of an ovum by which it was absorbed months before, unless the ovum possesses some special power of preserving, not only its own latent power, but the potency of the sperm on which it depends for the special growth intended by nature. The second explanation of this supposed influence of a previous sire is, that there is an interchange of constituent parts of the fetal and maternal blood-currents. The exact amount of interchange between the two currents is not defined. We know that, on the one hand, certain constituents of the mother's blood connected with the nutrition of the fetus and oxygenation of the fcetal blood, pass from the mother's blood to that of the foetus; and, on the other hand, that certain constituents of the fetal blood connected with the removal of effete and excre- mentitious products pass from the fetus to the maternal blood- current by means of the placenta. It is asserted that some part of the fetal blood enters the maternal circulation, not 262 DR A. L. BELL. perhaps as blood, but in one form or other; but, at any rate, in whatever form it may enter the maternal blood, it is asserted that the fetal element thus given up to the mother is kept by her and enables the mother to impress the characteristics of the offspring of a previous sire on subsequent offspring got by a different sire; that is to say, the first sire impresses his own offspring with certain of his own characteristics; the offspring of this sire impresses the mother through the blood-current; the mother, in turn, transmits the peculiarities of the first sire to her subsequent progeny by means of the blood element she is said to have received from her first offspring. Let us suppose for a moment that this influence of a previous sire exists in fact, and that the explanation here quoted is the correct one. We are driven, then, of necessity to the conclusion: 1st, That the fetus actually gives up to the mother, besides the waste products, some essential part of its blood, carrying with it the key to hereditary transmission, for it is impossible that the effete material passed from the foetus to the mother can carry any such power. 2nd, If so, then the blood of the mother must become more and more mixed with each succeeding pregnancy, and be liable therefore to impress on her offspring the peculiarities, not of one sire only, but of every previous sire to whom she has borne offspring. It is impossible adequately to comprehend where such a theory would lead us. It is fortunately not necessary now to discuss the ultimate ramifications of such a far-reaching and, as it seems to me, unnatural process, so utterly at variance with what we know of the definiteness of the physiology of nature. The theory which was at one time advanced by M'Gillivray in the Monthly Journau of Medical Science for October 1850, that the influence of a previous sire was due to an actual transfer of blood from the foetus to the mother, cannot be entertained, because it has been proved beyond cavil or dispute that in ordinary circumstances, at least, no commingling of the maternal and fetal currents can take place, and that the two currents are not only distinct from each other at first, but remain so up to the very end of pregnancy.