PREFACE 



THE idea of writing this little book occurred to me 

 whilst reading Mr. W. C. D. Whetham's volume on 

 ' The Recent Development of Physical Science.' T 

 found the story of the modern progress of physics so 

 interesting as to encourage the belief that a similar 

 account of the subjects with which I was myself more 

 particularly familiar might prove of a like interest to 

 other people. I did not, indeed, suppose for a moment 

 that I could vie with Mr. Whetham in the power of 

 literary expression which renders his book so eminently 

 readable. I rather hoped that the peculiar interest 

 and importance of the theme might outweigh the 

 present author's deficiencies in this respect. 



For the group of subjects of which I intended to give 

 a brief account Mr. W. Bateson has recently proposed 

 the term ' genetics,' an expression which sufficiently 

 indicates their scope to the initiated. Since, however, 

 the meaning of the word ' genetics ' is not yet clearly 

 understood by everybody, it seemed better to adopt 

 in the present instance a somewhat more descriptive 

 title. 



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