VI PREFACE 



Plant Breeding, Bailey's Plant Breeding, and the Proceedings 

 of the American Breeders' Association. 



It is a pleasure to me to express my thanks here to Dr. Mc- 

 Clung and Dr. Billings for suggested improvements in Chapter 

 XIII, to Mr. Peace for improved processes in microtechnic, and 

 to Miss Eugenie Sterling for the drawings in Chapter XIII. 



W. C. STEVENS. 



UNIVERSITY OF KANSAS. 

 October, 1910. 



