THE

Journal of Health and Disease.

APRIL, 1846.

PHYSIOLOGY IN REGARD TO THE LAWS OF INCREASE AND THE INFLUENCE OF PARENTS ON OFFSPRING.

CHAPTER IV.

SECT. I.-The conditions under which healththy offspring can be obtained.Illustrations from the vegetable kingdom.-Degeneracy of the Potato.-The Dahlia.-Animal kingdom.-Breeding in and in.—Short horned cattle.-Breeds of Dogs.-Talbot hounds.

THE truth that parents modify the offspring has been illustrated by evidences sufficiently numerous to set aside all dispute.

These evidences have had reference principally to one point of view-namely, that certain peculiarities are transmissible. But there is another point of view, which has even a higher bearing-namely, what are the general conditions of the parents themselves, under which a proper progeny may be expected; or, placed in another form, what are the general conditions under which parents must be, in order to avoid begetting inferior offspring?

It may be useful to ascertain whether, from the vegetable kingdom may be obtained some facts which will throw light on this important subject.

It is well known, that seeds, planted for successive years in the same soil, degenerate: the size of the seed diminishes; its productiveness is lessened.

Farmers understand this fully: hence one reason why a rotation of crops is useful.

Mr. Paton, in his remarks on the degeneracy of the potato, has the following:

"We now come to what I consider the very root of the evil -namely, a predisposition in the potato itself to receive the disease in question. This predisposition I conceive to result from its having degenerated in consequence of having been sub

jected to a long course of ARTIFICIAL cultivation; and therefore, that our attention must be directed mainly to the means of preventing this degeneracy, while we endeavour to remove all such external causes of the disease as may be under our control. That the potato, in common with all other cultivated productions of the vegetable world, has a tendency to degenerate when the laws of nature are deviated from, must be granted; and, considering that it is not a native of this country, it is reasonable to expect that it will degenerate in proportion as means are neglected to prevent it from doing so.

"This tendency to degenerate is well known to exist even in trees which are cultivated by grafting; and to such an extent that many of the first sorts of apple-trees, which were formerly cultivated with the greatest care, have long since become entirely worthless.

"With respect to the potato, nature clearly seems to have made provision for the permanent health, as well as for the productiveness, of her own offspring, in the seed contained in the berry which the plant produces from its stalks; and, conse quently, by our endeavouring to perpetuate any particular sort of potato, by continually cutting and planting its tubers, it is reasonably to be expected that we shall injure its general properties and powers, and thus gradually render it less fit for food, and more liable to disease.

"If the foregoing observations should be deemed correct, it will follow, that in order to be as certain of obtaining as good a crop of potatoes as it is possible to be, the ground, before being planted, should be thoroughly pulverized; the manure should be well fermented; the sets should be whole potatoes, and never deprived of their first shoots, nor allowed to ferment; and, lastly, that a constant succession of new sorts should be raised from the berries of the old ones. The newly raised sorts would doubtless admit of being cut with safety for several years, and would be but little affected by other external injuries, unless peculiarly delicate, as they would possess all the health and vigour of a plant propagated according to nature's laws. By attending to these few suggestions, the experience of several years of extensive observations warrants me in saying, that a full crop of potatoes

may, under all ordinary circumstances of the weather, at all times be secured. I would, however, particularly recommend the raising of a succession of new sorts from the seed contained in the berry of the most approved old ones, as I firmly believe that the disease complained of is mainly to be attributed to this having been too generally neglected. In the year 1833, I raised from the berry a great variety of new sorts. In 1834, the best of them were selected and planted separately. At the present time, although planted late and cut, they are displaying an extraordinary degree of health and vigour; while, in the same field, and almost by the side of them, some of the old sorts are not only feeble, but both TAINTED and CURLED; thus unanswerably proving the necessity of having recourse to the assistance of nature to counteract the evils arising from a long course of artificial, and in some respects injudicious, cultivation." 50

Horticulturists understand this. Mr. Heriot thus writes on the culture of the dahlia:-"Some persons allow them (the bulbs) to remain all winter in the ground, and, if the frost prove severe, cover the bed with mulch, or dung, or straw; and, if the winter prove very mild, like the winter 1833-34, this may be done without the loss of the plants; but a gardener in this neighbourhood, who did so, has had almost all his plants flower single the following season, although this may have proceeded from other causes. "" And he adds in a note, in reference to this, "I incline to ascribe it to the exhaustion of the ground: as plants which have once flowered double, can be brought back to double flowers by change of soil and manure." "1

51

If this degenerating condition exists in relation to the forms under which vegetable life is presented, there is little reason to doubt that it will exist in a greater ratio in regard to the forms of animal life. The phenomena will be found presented in connexion with the union of those nearly related; otherwise called,

BREEDING IN AND IN.

The following facts illustrate well, by the benefits arising from not breeding in and in, the evils which must result when this latter practice is adhered to.

Mr. Dickson, in his valuable essay on "Short Horns," remarks, "It would be an interesting investigation to ascertain

how the short-horns have been enabled to originate, maintain, and extend apace the celebrity which they have so long enjoyed. I fear such an investigation cannot be pursued with much satisfaction for the origin of this breed, like all other existing breeds of cattle, is enveloped in obscurity. All that we know of the mode of maintaining the proved good qualities of any domesticated breed is to preserve the purity of its blood. In practical language, purity of blood means freedom from an immediate intermixture between different varieties of cattle; and it is preserved in practice in the highest degree by the union of selected males and females, free from that immediate intermixture and close relationship." 52

It appears that this famous breed was obtained by bringing over from Holland some Dutch cows and bulls, and crossing them with the Tees-water cattle,-a race of cattle on the banks of the Tees in the counties of Durham and York. "Amongst the earliest importers of Dutch bulls and cows was Sir William St. Quintin of Scampston. The cross produced by the imported breed is said to have made a decided improvement on the old; and following up the advantage, the cross at length produced a stock distinguished by the name of the 'Teeswater Short-horns,' a stock which united in a wonderful degree the good properties of graziers and milkers. These valuable properties were soon appreciated, and cherished with uncommon zeal among rival breeders."

Mr. Dickson thus proceeds, "The preservation of the valuable breed of short-horns is a consideration of paramount importance, and, fortunately, it is in the power of breeders themselves to secure it. It consists entirely in maintaining the purity of blood in vigour. This desirable end is best secured by avoiding, on the one hand, the evil of breeding in-and-in-that is, the union of too close relationship in blood, and, on the other, too violent a cross. A strong mark of purity of the blood being in vigour is the circumstance of like producing its like; and no breed will, in this respect, incur so little disappointment to the breeder as short-horns, after a proper selection of the dam and the sire.

"The evil of breeding in-and in, or, in other words, producing too great refinement of tone, is manifested in the first instance

by a tenderness of constitution; the animals not being able to withstand the extremes of heat and cold, rain and drought. If the evil is prolonged through several generations, the forms of of the animals become affected, the bone becomes very small, the neck droops, the skin of the head becomes tight and scantily covered with hair, the expression of the eye indicates extreme sensibility, the hair on the body becomes thin and short, and the skin as thin as paper; the points continue good, and predisposition to fatness increases, but the whole carcase becomes much diminished in size, though retaining its plumpness and beautiful symmetry. The evil, however, does not terminate in the production of these symptoms. Internal diseases ensue, such as disorganization of the liver, or rot, polypi in the trachea, or clyers, malformation of the bones of the neck and legs, and general deformity."

In fact, the benefit of uniting the Scotch cattle with the English, in producing a good breed, Mr. Dickson recognises, when he remarks, "Breeders in Scotland have now greater reason than ever to drink

Perhaps a more illustrative exhibition of the evil influence of nearness of blood could not be afforded than that presented in the following interesting account of the consequences of breeding in and in:

:

It is in a tale of Job Sykes, the huntsman, and has reference to four horse-shoes suspended on the wall of his sitting-room, which had been placed there by his grandfather, who held, a century ago, the same post held now by Job under the Squire of the Range.

"In the olden time, land now cropped with corn, and through which the ploughshare yearly cuts deep furrows, was nothing but wood and waste, and kept as hunting grounds for the wild boar and stag; and great meres covered with tall flags, rushes, and rank grass, now drained and dry, were haunts for the heron, preserved for the noble sport of falconry.

"The Squire of the Range, with whom Jacob Sykes lived, was the first, in these parts, to commence felling scores of broad