Page:Contraception; 1st ed. (IA in.ernet.dli.2015.94163).pdf/242

tion either all their statistics or their deductions, several of their main arguments are substantially correct. Many others, of course, have dealt with various aspects of this subject, and by a study of the ordinary published statistics it is easy to ascertain that the survival rate is distinct from the birth and death-rates, and nationally is the most important factor.

In spite of the "decline in our birth-rate" our total number of births is steadily increasing as the size of the population grows. Speaking before the Eugenics Education Society a year or two ago I gave a very simple illustration to show that the birth of each child sends up the birth-rate for one year and sends it down for approximately twenty years! This point is generally overlooked, but should be borne in mind, so I will repeat the illustration:—

A healthy young couple are cast away on a comfortable uninhabited island yielding food and shelter in plenty. Total population 2. A child is born to them: birth-rate 50 per cent. Total population 3. A second child is born, but this time the birth-rate is not 50 per cent. of the total population, but only 33½ per cent. Total population 4. Another child