A variety still more extended, and to which naturalists have given more of character than it really deserves, is the form of the horns; they have not considered that, in our domestic cattle, the shape, size, position, direction, and even number of horns, vary so strongly, that it would be impossible to pronounce which is the true model of Nature. The horns of some cows are curved and bent downwards; others have them straight, long, and elevated. There are whole races of sheep, who have sometimes two, sometimes four horns, and there are breeds of cows who have no horns. These exterior, or, as I may say, accessory parts of the body, have as little permanency as the colours of the hair, which in domestic animals vary and combine in every manner. This difference in the shape and direction of the horns, which is so common, must not then be regarded as a distinctive character of the species; though, it is upon this character alone that our naturalists have established their species; and, as Aristotle, in the description he gives of the bonasus, says, that its horns turn inwards, they have from that alone separated it from all other oxen, and made it a particular species, without having ever seen the individual. Upon this variation of the horns, in domestic animals, we have quoted cows and ewes, rather than bulls and rams, because the females are more numerous than the males, and we may every where observe thirty cows or ewes for one bull or ram. The mutilation of animals by castration seems to hurt the individual only, and not to affect the species; nevertheless, it is certain, that this custom restrains Nature on one side and weakens it on the other. A single male, condemned to serve thirty or forty females, must exhaust himself without satisfying them. The ardour of love must be unequal; indifferent in the male, who exceeds the designs of Nature, and too ardent in the female, who must be so limited; from thence all the productions must chiefly be tinctured with feminine qualities, a greater number of females will be produced than males; and even the males possess more of the mother than the father. This is, without doubt, the reason there are more girls than boys born in the countries where men have a great number of wives, while among those where the men are permitted to have but one, more males than females are born. It is true, that among domestic animals they commonly withhold the most beautiful from castration, to become the parent of a numerous generation. The first productions of these chosen males will be strong and vigorous; but from having too many copies from this single mould the impression of Nature is deformed, or at least impaired, and not preserved in its full perfection; the race must, therefore, be weakened and degenerate; and this, perhaps, is the cause why more monsters are to be found among domestic than wild animals, where the number of males, which concur to generation, is equal to that of the females.