The animals of incestuous broods were much smaller and lighter than others, and their fecundity was diminished.[1986] Mr. Huth himself observed, when breeding rabbits in-and-in, that “after the fourth generation there was a diminution of fecundity analogous to the disgust that the stomach would feel at the same diet long continued,” though he found no evil effect in any other way. On the contrary, the in-and-in bred offspring were somewhat heavier than the non-related parent animals.[1987] Professor Preyer has made a similar observation with regard to guinea-pigs: breeding in-and-in produced a considerable loss of fertility, but was accompanied with an increase of weight.[1988] This seems to indicate that the effects of close interbreeding are not always the same. There are certainly breeders who prefer connecting together the animals nearest allied in blood to one another. But, as Dr. Mitchell observes, “when breeding in-and-in has been practised with so-called good results, the issue is nothing but the development of a saleable defect, which, from the animal’s point of view, must be regarded as wholly unnatural and artificial, and not calculated to promote its well-being or natural usefulness.”[1989] Many writers suppose that all the evils from close interbreeding depend upon the combination and consequent increase of morbid tendencies common to both parents, the state of whose health decides whether union would be favourable or not to the offspring. “If the parents are perfectly healthy,” says M. Pouchet, “and exempt from all commencing degeneracy, they can only give birth to children _at least_ as healthy as themselves.... But if the same degeneracy has already tainted both the parents, the offspring will show it in a greater degree, and will tend towards entire disappearance.”[1990] The same opinion is held by Sir John Sebright. But being, as an experienced breeder, well aware of the injurious results which almost always follow from interbreeding animals too closely, he adds that, according to his belief, there never did exist an animal without some defect, in constitution, in form, or in some other essential quality, or that at least a tendency to the same imperfection generally prevails in the same family.[1991]