(1) WORLD POPULATION AND ITS DISTRIBUTION (a) Geographical Distribution.—The best known estimates of the population of the world are those of the International Statistical Institute. In Table I. are given the estimates of the institute for the world as a whole and for the five continents about the years 1920 and 1926. It never happens that there is up-to-date information for every country in the same year. The data avail able nearest the year named are used and therefore in the table the word "about" is introduced. To what extent can these estimates be relied upon? There is a certain margin of doubt. The estimate for the institute for 192o is 1,811 millions, while the independent estimates of the International Institute of Agriculture for 1921 and 1925 are 1,82o and 1,871 millions re spectively. Other independent estimates show no very serious divergences and it is not likely that the totals are greatly in error. When we come to examine the estimates for each con tinent we find that the figures for Europe and North America may be taken as approximately accurate, though some doubt arises concerning Russia and Mexico. The figures for Oceania are probably more accurate than those for any of the other re maining areas. While very considerable progress has been made in the enumeration of the inhabitants of certain South American countries, especially of Brazil, Argentina, Chile and Uruguay, there remains a large measure of doubt concerning the total population of the Southern half of the American Continent. The figures for earlier dates are still more open to suspicion, and the relatively large increase in the total population which would appear to have taken place during the present century is probably in part due to incomplete enumeration at earlier dates.
The figures for Asia are still less trustworthy. For some Asiatic countries there are reliable figures. One of the greatest achieve ments in the history of the enumeration of peoples has been the taking of a census in India. But important as is India from the point of view of numbers, China is still more important. Until
recently, estimates of the population of China differed by more than a hundred millions. They still differ widely but there is a general tendency among those who have given most study to the matter to accept a high rather than a low estimate. In 1921 an estimate of 445,000,000 was made for China, Manchuria and the Chinese dependencies by the Chinese postal administration, and this estimate agrees closely with those made by the Chinese mari time customs for 1922 and by the China Continuation Com mittee for 1918. Those who accept lower estimates have ap parently been influenced by the census of 191o. This was a census of households and not of persons and in order to obtain the number of persons it is necessary to multiply by a factor—a proceeding which leaves the results open to a wide margin of error. The estimate by the International Statistical Institute of the world population in 1926 includes a figure of 433,000,000 for China and this figure is based upon special information fur nished by the Chinese Minister of the Interior. It is evident that in view of the uncertainty regarding the population of China and of the tendency to accept higher estimates, no great im portance can be attributed to the apparent growth of the popula tion of Asia in recent years which figures generally show. Simi larly no confidence can be placed in the figures which seem to show a decrease in the population of Africa during the last half century. The estimates for this continent are less trustworthy than for any other continent. It would seem that in the last century observers tended greatly to overestimate the negro population. These estimates have since been considerably reduced and this reduction accounts for the apparent decrease in the population of the continent. At the same time parts of the con tinent have been ravaged by sleeping sickness and other diseases in late years and it is thus unlikely that there has been any true increase in the population.