There are several isolated communities—in Java, Peru, Great Britain, France, Scandinavia, &c.—which intermarry solely among themselves without any evil effects being discernible. An often-quoted case is the community of Batz (3,300 persons), situated near Croisic on a peninsula. The inhabitants of this community have been in the habit of closely intermarrying among themselves from time immemorial. Nevertheless, they are almost all very well in health without any hereditary affection. But Dr. Voisin observes, “Les conditions climatériques de la commune de Batz, son voisinage de la mer, l’hygiène et les habitudes de ses habitants, semblent s’accorder pour empêcher la dégénérescence de l’espèce et paraissent expliquer l’innocuité des mariages entre consanguins qui s’y pratiquent depuis plusieurs siècles.”[2015] In other isolated communities the population is not so numerous, and the sanitary conditions are not perhaps so favourable: but in any case we may say that this local endogamy is generally something quite different from marriage with near relations. Dr. Mitchell found that, in almost all the isolated communities along the coasts of Scotland, which had been given as instances of close interbreeding, such marriages were comparatively rare. According to Dr. Mygge, the like is true of the population of Lyø and Strynø in Denmark.[2016] And Dr. Andrew Wood states, of the fisher-folk of Newhaven, that, though they keep themselves much segregated, they are very careful regarding intermarriage, and look upon the union of relatives as an infringement of the laws of morality.[2017] Moreover, even if it could be proved that, in particular cases, close intermarrying, though continued for a long time, has been followed by no bad consequences, this would be no evidence that consanguineous marriages are as a rule innocuous. In some parishes of Denmark Dr. Mygge found no evil effects of such marriages, whilst in others they were very conspicuous.[2018] And from the investigations of Mr. Darwin it appears that, notwithstanding the injury which most plants suffer from self-fertilization, a few have almost certainly been propagated in a state of nature for thousands of generations without having been once intercrossed. It is impossible to understand, he says, why some individuals even of the _same species_ are sterile, whilst others are quite fertile, with their own pollen.[2019]