CONTENTS 11 



PAGE 



India, China, and Egypt there is evidence that the factors are not 

 effective, and that over-population occurs. (6) In the third sub- 

 group, where the factors are different, (7) we can see in disabilities 

 placed upon serfs, and (8) in difficulties, (9) restrictions, and (10) Poor 

 Law provisions hindrances to marriage. (11) The system was 

 generally effective, though over-population occasionally occurred. 



(12) In the fourth sub-group there is no evidence of over- population ; 



(13) the factors are rather different, and (14) pressure comes about by 

 unconscious response to economic conditions. (15) Summarizing the 

 position for all groups we find that owing to the great power of increase, 

 customs restrictive of increase are always necessary, and (16) have 

 taken various forms (17) with varying effectiveness. (18) Changes 

 in qixantity are a result rather than a primary cause of historical 

 events. (19) Neither migration (20) nor war is due directly to over- 

 population, though the position as regards quantity may be an 

 element in the situation predisposing nations towards migration 

 and war. 



CHAPTER XII 



SOME MODERN PROBLEMS 308 



(1) The recent increase in numbers was in response to economic 

 requirements, and affords no ground for pessimism as to the future. 

 (2) The density desirable may be considered from the point of view 

 of moral welfare (3) and of national safety, as well as from the economic 

 standpoint. (4) The importance of minor fluctuations. (5) Methods 

 of limiting increase at the present day. (6) Different ratios of increase 

 as between different classes, (7) between different races in the same 

 country, and (8) between different countries. 



CHAPTER XIII 

 THE QUALITATIVE PROBLEM 322 



We have to ask how far those changes which constitute history are 

 due to germinal changes, and are therefore comparable to changes 

 among species in a state of nature. Analysis of remaining chapters, 



CHAPTER XIV 



THE INFLUENCE OF THE ENVIRONMENT AMONG ANIMALS 



AND PLANTS 325 



(1) Observations show that environment and heredity are com- 

 plementary one to the other. (2) Abnormal stimuli may produce 

 almost any result, but (3) for each species there is a normal environ- 



