viii Preface 



collaborated with me. A beautiful series of results, especially 

 relating to the heredity of Stocks (Matthiola), has been the 

 fruit of her labours exclusively. Not only have these 

 results greatly advanced our knowledge of genetic pheno- 

 mena, but I think that at a time when Mendelism was, in 

 England at least, regarded with suspicion, the obvious 

 precision of her work and the persistence of her advocacy 

 did much to convince the scientific world of the reality of 

 our assertions. 



In 1904 I had the good fortune to gain Mr R. C. Punnett 

 as a partner. Since that date we have worked in close 

 collaboration, and the work that we have thus done has 

 been in every sense a joint product, both as regards design, 

 execution, and interpretation of results. Though for the 

 presentation of the views contained in this book I am solely 

 responsible, those that apply to the subjects of our own 

 work are often his, or have been arrived at in consequence 

 of interchange of ideas with him. 



On some points of general physiology I have received 

 useful suggestions and criticism from Mr F. F. Blackman, 

 and in this respect I am also especially beholden to 

 Miss F. M. Durham. 



The Plates of Sweet Peas and Mice are photographic 

 reproductions, on the whole very accurate, of coloured 

 drawings most kindly made for me by Miss Wheldale. 

 The Plate of Primula flowers is taken from an excellent 

 coloured photograph by Mr Waltham*. For Fig. 9 I am 

 obliged to the New Phytologist. 



For several years past I have had an exceptional 

 opportunity of seeing breeding conducted on a large scale 



* Since the word " magenta," often used in English for the description 

 of a colour, is not understood on the Continent, I may say that it means a 

 purplish or bluish red, as distinguished from a crimson or pink red. On 

 Plate VI, Figs. 8, 9, 14, 15, 20, 21 represent shades of magenta, while 

 Figs. 2, 7, 13, 19 are true reds. 



