Page:Popular Science Monthly Volume 45.djvu/784

 women have no children, only 3·5 per cent of the half bloods are childless. The proportionate number of half bloods who have one, two, three, four, or five children is smaller than the corresponding number of Indian women, while many more half-blood women than full-blood women have had from six to thirteen children. This distribution is shown clearly in Fig. 1, which



represents how many among each one hundred women have a certain number of children. The facts disclosed by this tabulation show that the mixed race is more fertile than the pure stock. This can not be explained by a difference of social environment, as both groups live practically under the same conditions. It also appears that the small increase of the Indian population is almost entirely due to a high infant mortality, as under better hygienic surroundings an average of nearly six children would result in a rapid increase. It is true, however, that a decrease of infant mortality might result in a decreased birth rate.

Among the Indians of the Pacific coast the infant mortality is also very great, but we find at the same time a still larger proportion of women who bear no children.

It is of some interest to note the average number of children of women of different ages as indicating the growth of families. Among the Indians there is an average interval of four years and a half as shown in the following table which, however, must not be confounded with an average interval between births:

Among the half bloods the interval is shorter, but the number of available observations is insufficient for carrying out the comparison in detail.