Population and Immigration.—In 1751, Benjamin Franklin wrote his “Observations Concerning the Increase of Mankind and the Peopling of Countries” and concluded that the importation of foreigners into a country does not necessarily increase the population; but that if the immigrants are more industrious and frugal “they will gradually eat the natives out”. This thesis is supported by W. A. Rollins (Jour, of Heredity, vol. 21, No. 9), who analyses the census changes in the United States since 1650 and their relation to immigration. He shows how the originally high fertility of the early colonial stock declined very slowly until about 1850, when there was a great increase of immigrants, after which the decline was rapid. He also shows that for different parts of the country a high rate of immigration coincided with a low birth-rate and vice versa, and that while the immigrants have been chiefly labourers, the fall in the birth-rate has been most marked among university graduates, the ultimate effect being the replacement of the educated stocks by immigrants and their descendants. The character of the population of New England has been deteriorating in this way at least since 1850 and probably earlier, and the author suggests that the cycles of civilisation are sometimes correlated with a differential birth-rate, the ascent taking place during a period when superior stocks have more children than inferior ones.