1268 LIFE : OUTLINES OF GENERAL BIOLOGY 



To avoid bad debts, to have hobbies, to cultivate new interests, 

 to make a new effort towards positive health — these are the ways to 

 prevent senescence becoming senility. 



So we see that we must cultivate health of body and mind with 

 renewed enthusiasm, so as to make the most and the best of every 

 stage in the trajectory which is so full of promise and yet so full of 

 risks. 



THE PROBLEMS OF POPULATION 



This subject of population, biologically regarded, is so difficult 

 that no apology is needed for putting what we have to say in the 

 somewhat unusual form of a series of questions and answers. 



What is the population of the earth? The population of the earth 

 is about 1,750,000,000 — though, of course, the census in some places, 

 such as China, is not very reliable. Is the world's population increas- 

 ing ? The absolute increase every year in the world's population is 

 about 12,000,000; some put it at about 14,000,000, some at 

 16,000,000, some as high as 20,000,000; we are quite safe in saying 

 that it is about 12,000,000 per year. This is an astonishing fact 

 when one remembers that Malthus, who lived about the time of the 

 French Revolution, stated that the population of the world was then 

 850,000,000. Thus the population of the world has doubled since 

 the date of Malthus. Suppose that mankind has been in progress 

 for half a million years! Millions were born and millions passed 

 away; yet the portentous fact is that the living population was 

 doubled in the last hundred years. 



7s the absolute increase in the world's population equally distri- 

 buted ? Very far from it. In the period between 1800 and 1910 the 

 increase in population in Russia and the United States, for instance, 

 was prodigious. During the same period the population in Great 

 Britain was trebled, an increase enormously greater than that of 

 some other European countries, such as Portugal. With regard to 

 the United States, one must remember that the total was swelled 

 by the tide of immigration. 



In the period from 1906 to 1926 careful inquiry into the statistics 

 of increase of population showed that if the rate of increase during 

 that period was maintained France would take 436 years to double 

 her population. On the other hand, in Canada, where the increase 

 was more rapid than in any other country, the population, if it went 

 on at that rate, would be doubled in twenty-four years. England 

 has doubled her population in sixty-seven years, and Germany in 

 fifty-one years, and so it goes on. 



We must consider the international aspects of the population 

 question as well as the national and family aspects. A very interesting 



