Page:Popular Science Monthly Volume 75.djvu/600

594 the higher classes are not exempt from this iron law. Various causes are mentioned for this fact. Marriages are contracted much later in life among the wealthy, and, as a rule, they have fewer children; the intellectual, life seems to be unfavorable to the fecundity of women. Race suicide is more common among the higher classes. It is hardly necessary to mention that families of an extremely healthy stock, and living under the most favorable conditions, are able to continue their existence a much longer time. The remarkable vitality of the British aristocracy is due to their athletic habits and to the fact that they spend the greater part of the year on their estates in the country. Ammon holds that the aristocratic classes of the continent "have favorable prospects to perpetuate their family names only if they live on their estates and devote themselves to agriculture and the chase."

The Jews seem to form an exception to what has just been said. They have been city dwellers from the time they left Palestine and began to overrun the countries of the earth. There can be no doubt that they are a very healthy race. In the struggle for existence, during the endless persecutions they had to undergo in every country and at all ages, only the strongest individuals survived. A process of natural selection thus produced a vigorous race. The frugal and sober habits and the faithful application of the sanitary precepts of the Mosaic code also contributed greatly to produce a healthy people. But these influences are much less at work in modern times. The vitality of the Jew will be greatly affected by modern city life as we find it in the city of New York, where the great bulk of the Jewish population in this country lives. Tuberculosis, the scourge of the white race, used to be rare among the Jews, but the unsanitary life in the "sweat-shops" of New York is also increasing its victims among this people.

The rate at which city populations die out is much more rapid than one would ordinarily suppose. Recent researches have thrown much light on this process of elimination. Ammon, in his researches on the population of Carlsruhe and Freiburg (two comparatively small cities) established the fact that the city-born population decreases in the course of two generations from 100 per cent, to 29 and 15 per cent. He supposes that on an average the families who move from the country to a city die out in the course of two generations. Hansen found that one half of the population of the German cities consists at all times of immigrants from the country districts, and he concludes from this fact that the city population renews itself completely in the course of two generations. We may safely apply these results, which have been