LIKE BEGETS LIKE.

Otago Witness, Issue 1994, 12 May 1892, Page 7

LIKE BEGETS LIKE.

Of late years the science of heredity has been closely studied by some of the leading scientists of the age, as well as by many others whose careful observation and wide experience atoned for their lack of theoretic knowledge. The imagination is bewildered, and the brain is dizzied by the revelations of astronomy, respecting the infinitely great in Nature ; but in examining the science of heredity, the investigator is brought face to face with substances which are infinitely little when measured by a geometric scale, but whose far-reaching influence is out of all proportion to their bulk. The leading principle of heredity is summed up in the well-known formula, "Like tends to beget like," subject to the modification caused by environment as well as that arising from the individuality of the offspring. But the way in which this result of like begetting like is brought about is at once wonderful and mysterious, In the animal economy, certain minute particles, discoverable only by microscopes of the highest magnifying power, are elaborated. These infinitely minute particles are the most complex substances known to science, for they contain the very essence of the life and physical as well as mental structure of the individual, and of his ancestors for many generations back. Each of these particles is enclosed within a germ cell, and the generating of a new individual is brought about by the fusion of one of these particles elaborated in the male body with a similar particle elaborated in the female body. These particles, so fused together, are technically known as the male pronucleus and the female prenucleus ; and the body, if it may be so called, which in formed by their fusion, is known as the segmentation nucleus. Under the influence of the life that flows into the new body, produced by the union of the male and female pronuclei, the cell surrounding this body multiplies by a process of division, and each new cell in turn multiplies by the same process, until by this division and multiplication of cells all the tissues and organs of the embryonic and adult body are produced. By a similar division and multiplication of cells the segmentation nucleus is diffused in a marvellously minute degree through every part of the body, and is in fact the medium by which the characteristics of the parents, and of their ancestors, are indeliblystamped upon the offspring. It frequently happens that one or other of the parents possesses a prepotency which results in the offspring showing a marked resemblance to that parent,

while it happens just as frequently that the offspring show a marked resemblance to some more remote ancestor.

It is also well known that heredity may be modified by influences of a very subtle nature. Thus the embryonic offspring is often powerfully acted upon by the excited imagination of > the parents, and more particularly of the mother. A prominent case in point is the fact recorded in Genesis, where the astute supplanter laid peeled rods before the flocks in order to influence the colour of the offspring. At the annual dinner of the Aberdeen - Angus Breeders' Association last year Sir George M. Grant narrated how once upon a time two cows were mated at Ballindalloch with the stock bull on the same day, and immediately in front of where the cows were standing at the time of impregnation a line of white clothes hung out to dry were waving in the wind. Both these cows calved the same week, and both dropped calves which were strongly marked with white, although none of their ancestors for many generations back had ever shown any white markings. Numerous similar cases might be quoted, and the influence of the excited imagination on the embryonio offspring cannot be questioned. But an equally curious and important fact is the influence that may be exerted on the future progeny of a female by the first fetus which she may bring to the birth. A remarkable instance of this is the oftcited case of Lord Morton, who had an Arab mare served with a Zebra. As a matter of course, the hybrid so produced was marked like a Zebra ; but the remarkable thing was that, although this mare afterwards produced two foals by an Arab sire, the produce in both cases were marked with the characteristic stripes of the zebra. In the same way it has been stated — though we do not know with what amount of truth— that in the early history of the Aber-deen-Angus breed, some breeders occasionally put their polled heifers to a shorthorn bull in order that the future produce of these same heifers by polled sires might have somewhat of the squarer quarters of the shorthorn breed. It is also well known to breeders of pedigreed stock that if a female has borne progeny to an inferior sire, her future progeny will show, in a greater or less degree, the characteristics of that same sire. It has not been easy to assign a j satisfactory cause for these results,- as it is only natural to conclude that when once a female has brought a fcetus to the birth, and reared that offspring, her organisation would be entirely clear from the influence of that offspring. Among the various explanations that have been j offered of these facts, Sir Wm. Turner has \ advanced one which is probably the best that physical science can offer. His explanation is to the effect that in placental mammals an

interchange of material takes place in opposite directions from the young to the mother, as well as from the mother to the young. In this way the germ-plasm of the mother, belonging to ova not yet matured, are modified while still lodged in the ovary of the mother, and this acquired modification would exert its influence on the future offspring derived from that germplasm. Whatever may be thought of this theory, it has at least the merit of plausibility. A study of the science of heredity cannot fail to impress the live stock breeder with the paramount importance of a good pedigree. If, by the laws of heredity, the characteristics of one or other or both of the parents, or of some more remote ancestor, are certain to be stamped Jon the offspring, the importance of breeding only from animals which are not only of high-class quality themselves, but are descended from stock of equally high quality, is at once apparent. The more distinguished and the more unsullied the lineage of any pair of animals are, the greater is the probability that the stock begotten of their union will be equal to themselves in quality. "Blue blood" is something more than the mere accident of birth and position. It is, in fact, practically a guarantee of the quality of the individual and his ancestors, and a gaurantee also of the perpetuation of that quality if the laws of heredity be observed. — North British Agriculturist.