The above are a few of the many instances on record tending to show the influence of a first impregnation upon subsequent progeny by other males. Not a few might also be given showing that the same rule holds in the human species, of which a single one will suffice here:--"A young woman residing in Edinburgh, and born of white parents, but whose mother previous to her marriage bore a mulatto child by a negro man servant, exhibits distinct traces of the negro. Dr. Simpson, whose patient at one time, the young woman was, recollects being struck with the resemblance, and noticed particularly that the hair had the qualities characteristic of the negro."
Dr. Carpenter, in the last edition of his work on physiology, says it is by no means an infrequent occurrence for a widow who has married again to bear children resembling her first husband.
Various explanations have been offered to account for the facts observed, among which the theory of Mr. McGillivray, V.S., which is endorsed by Dr. Harvey, and considered (as we shall presently see) as very probable at least by Dr. Carpenter, seems the most satisfactory. Dr. Harvey says:
"Instances are sufficiently common among the lower animals where the offspring exhibit more or less distinctly over and beyond the characters of the male by which they were begotten, the peculiarities also of a male by which their mother at some former period had been impregnated. * * * Great difficulty has been felt by physiological writers in regard to the proper explanation of this kind of phenomena. They have been ascribed by some to a permanent impression made somehow by the semen of the first male on the genitals and more particularly on the ova of the female:[11] and by others to an abiding influence exerted by him on the imagination and operating at the time of her connection subsequently with other males and perhaps during her pregnancy; but they seem to be regarded by most physiologists as inexplicable.
Very recently, in a paper published in the Aberdeen Journal, a Veterinary Surgeon, Mr. James McGillivray of Huntley, has offered an explanation which seems to me to be the true one. His theory is that "_when a pure animal of any breed has been pregnant to an animal of a different breed, such pregnant animal is a cross ever after, the purity of her blood being lost in consequence of her connection with the foreign animal, herself_ BECOMING A CROSS FOREVER, _incapable of producing a pure calf of any breed_."