Another very much in-and-in bred people are the Persians. Among them, husband and wife are generally of the same family, and very often cousins. Yet Dr. Polak who has lived in Persia for nine years, partly as a teacher in the medical school of Teheran, partly as physician to the Shah, and during this residence has had excellent opportunities of acquainting himself with the conditions of the people, has not observed that the diseases which are supposed to result from consanguineous marriages prevail more frequently there than elsewhere. Nor has he found that the Persian women are generally less fertile than others. Yet the families are exceedingly small, as the mortality among children is enormous. Of six, perhaps two as a rule survive, but very often none at all, most of them dying in their second year. Dr. Polak believes, indeed, that, on an average, scarcely more than one living child comes to each woman. A princess in Teheran was looked upon quite as a wonder because she had eight children alive, and the European physician was asked if he ever before, in his own country, had seen a similar case.[2044] More important than any of these statements is the following testimony concerning the Karens of Burma, for which I am indebted to the Rev. Dr. Alonzo Bunker, who has been a resident among that people during more than twenty years. He says that, in some of their villages, exogamy prevails, in others endogamy, but marriages between parents and children, brothers and sisters, are prohibited everywhere, and even first cousins very seldom marry, though there is no law against such connections. There is a striking difference with regard to stature, health, strength and fecundity, between the inhabitants of the exogamous and those of the endogamous villages, the latter being much inferior in all these respects. Dr. Bunker has no doubt that this inferiority is owing to the intermarriage of kinsfolk, and he asserts that even the natives themselves ascribe it to this cause, though they obstinately keep up the old custom, regarding marriages out of their own village as highly unbecoming. In cases in which missionaries have been able to persuade young men to choose wives from another village, Dr. Bunker assures me that the good effects of a cross appeared at once.[2045]