Mr. Colman, in an article on live stock, says, "There seems to be a limit beyond which no person can go. The particular breed may be altered and improved, but an entirely new breed cannot be produced; and in every departure from the original there is a constant tendency to revert back to it. The stock of the improved Durham cattle seems to establish this fact. If we have the true history of it, it is a cross of a Teeswater bull with a Galloway cow. The Teeswater or Yorkshire stock are a large, coarse-boned animal: the object of this cross was to get a smaller bone and greater compactness. By attempting to carry this improvement, if I may so call it, still further by breeding continually in and in, that is, with members of the same family, in a close degree of affinity, the power of continuing the species seems to become extinct; at least it approximates to such a result. On the other hand, by wholly neglecting all selection, and without an occasional good cross with an animal of some foreign blood, there appears a tendency to revert back to the large-boned, long-legged animal, from which the _improvement_ began. "There are, however, several instances of superior animals bred in the closest affinity; whilst, in a very great majority of cases, the failure has been excessive." Overtaxing the generative powers of the male is another cause of deterioration. The reader is probably aware of the woful results attending too frequent sexual intercourse. If he has not given this subject the attention it demands, then let him read the records of our lunatic asylums: they tell a sad tale of woe, and prove to demonstration that, before the blast of this dire tornado, _sexual excess_, lofty minds, the suns and stars of our intellectual world, are suddenly blotted out. It spares neither age, sex, profession, nor kind. Dr. White relates a case which substantiates the truth of our position. "The Prince of Wales, who afterwards became George the Fourth, had a stud horse of very superior qualities. His highness caused a few of his own mares to be bred to this stallion, and the produce proved every way worthy of the sire. This horse was kept at Windsor for public covering without charge, except the customary groom's fee of half a guinea. The groom, anxious to pocket as many half guineas as possible, persuaded all he could to avail themselves of the prince's liberality. The result was, that, being kept in a stable without sufficient exercise, and covering nearly one hundred mares yearly, the stock, although tolerably promising in their early age, shot up into lank, weakly, awkward, good-for-nothing creatures, to the entire ruin of the horse's character and sire. Some gentlemen, aware of the cause, took pains to explain it, proving the correctness of their statement by reference to the first of the horses got, which were among the best horses in England."