PREFACE 



THE object of this book is to give a succinct account 

 of discoveries in regard to Heredity made by the 

 application of Mendel's method of research. Following the 

 clue which his long lost papers provided we have reached a 

 point from which classes of phenomena hitherto proverbial 

 for their seeming irregularity can be recognized as parts of 

 a consistent whole. The study of Heredity thus becomes 

 an organised branch of physiological science, already abun- 

 dant in results, and in promise unsurpassed. 



A translation of Mendel's two papers, together with 

 a biographical note, is appended. The translation of the 

 first, based on a draft prepared for the Society by Mr C. T. 

 Druery, was printed in the Royal Horticultural Society's 

 Journal, 1901. With modifications I published it separately 

 in 1902, giving a brief summary of Mendelism as then 

 developed, under the title Mendel's Principles of Heredity : 

 A Defence. The object of that publication was to put 

 Mendel's work before the English speaking peoples and to 

 repel the attack which the late Professor Weldon had 

 recently made on Mendelian methods and the conclusions 

 drawn from them. The edition was at once sold out, but 

 I did not reprint the book. As a defence it had served 

 its purpose. Moreover the progress of experiment with 

 the extension of Mendelian conceptions was rapid, and the 

 account of those conceptions there given was in some 

 important respects soon out of date. In particular my 

 view of the nature of compound factors was shown to be 

 unnecessarily complex and largely incorrect. Though 



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