AUTBOR S PREFACE AXD ACKXOfi'LEDGilEyTS xi 



is given in detail to tlie U. S. Department of Agriculture 

 and to those Experiment Stations that contributed jjhoto- 



graphs for this volume. 



J. F. DUGGAR. 

 AuBUEX, Alabama, 

 January 2, 1911. 



