PREFACE vii 



or physiological relations, and not till this has been accomplished 

 will* it be possible to build on sure and firm foundations, and 

 to make a profitable study of the laws which govern the inherit- 

 ance of the various points both individually and in combination. 

 The truth of these propositions is abundantly illustrated in 

 the pages of this book, in which the author has set forth the 

 results of his long and varied experience as a practical farmer 

 and as an investigator and teacher of scientific agriculture. 

 The importance of Chemistry and Botany to agricultural 

 practice has long been recognized; the application of physio- 

 logical science, which hitherto has been almost wholly limited 

 to the domain of nutrition, is equally essential to a sound animal 

 husbandry. If this country is to maintain its present leading 

 position as a producer of high-class live-stock and at the same 

 time to keep up a due supply of meat and milk for national 

 consumption, it will be necessary to utilize every possible 

 advantage that can be derived from the study of biological 

 science. 



F. H. A. MARSHALL, 

 March, 1919 



