Preface 



In a study of the developmental period, one 

 must start with a background relating to in- 

 fluences that precede the beginning of inde- 

 pendent life and which tend to give it a good 

 or bad start. With this in mind, I have briefly 

 sketched the views of some leading biologists 

 on the subject of heredity, and have freely 

 drawn upon various authorities who have writ- 

 ten on the subjects discussed. Their names, 

 with references, are mentioned in the text, and 

 I herewith express my obligation to them. 



As to the factors that control life after it has 

 begun, those occurring in the early years are 

 the ones that specially count. Hence this 

 period of life must be particularly stressed in 

 a study of the possibilities of development. It 

 is also well to know what to expect when con- 

 ditions 'are favorable and how to recognize 

 disastrous influences in time for correction. 



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