Page:Popular Science Monthly Volume 63.djvu/93

Rh daughter and a younger son and the most common family of three would be two daughters and a younger son. Apparently no such statistics have been collected or even proposed.

The alleged causes of the small families in France do not seem to obtain in New England. It is extremely improbable that all parents should voluntarily limit the size of families; the decreasing family must be in part due to physiological causes, which may be individual or racial. Individual causes may be late marriage, especially of women, school life and other unhygienic conditions, or an inhibition exerted by intellectual and other interests outside the family.

Racial sterility is certainly possible. It seems to conflict with the principle of natural selection, as fertility might be supposed to have a high selective value. Natural selection, however, can only select, it can not produce variations. If size of head is more variable than size of pelvis and is equally important for survival, the increasing difficulties of childbearing are not inexplicable on the theory of natural selection. If sterility increases, we must assume that the conditions of the environment have altered too rapidly for variation and natural selection to keep pace with them. Indeed the existing conditions may be due in part to our interference with natural selection. The decreasing death rate on which we pride ourselves may in part be responsible for the decreasing birth rate. When children who can not be born naturally or can not be nursed survive, we may be producing a sterile race. No statistics in regard to miscarriages are at hand, but there is good reason to believe that they increase as the number of children decreases. There is no positive proof of race senescence in man. On the contrary we know that the Italians and the French Canadians have large families, though there is as much reason for them to suffer from racial exhaustion as the inhabitants of France, and the Chinese seem to be in no danger of extermination. But we know that animals bred for special traits tend to become infertile, and selection for our civilization may have the same result. Physicists tell us that the earth may be uninhabitable in twenty million years; it may be uninhabited by man in twenty centuries.

Field Columbian Museum, of Chicago, has now been in existence for ten years and has during this period made important progress. It was organized in 1893 at the close of the exposition, from which it received its building and some of its collections. The following year the name 'Field Columbian Museum' was adopted, owing to the generous gifts made by Mr. Marshall Field. The building erected for temporary purposes is gradually falling to pieces, and it is said that Mr. Field will provide a new building, which will surpass that of the American Museum of Natural History in New York City and the new building for the U. S. National Museum, for which congress has recently appropriated three and a half million dollars. The report of the director of the Field Columbian Museum for last year describes important increases in the collections and improvements in their arrangement. The collections have been largely secured through sixteen expeditions sent to different parts of North America. Ethnology seems to have been specially favored, nine expeditions under the charge of Dr. George A. Dorsey and other members of the staff having made extensive collections in Oklahoma, New Mexico, Montana, California and Alaska. Two collections were also purchased, one of which contains fourteen hundred specimens from the Tlingits of Alaska. In the department of botany the herbarium has been augmented by over twenty thousand sheets, and the