Authors' Acknowledgments 



Acknowledgment is gratefully made to the Minister of 

 Agriculture, Canada, for the illustration on page 247; the 

 United States Department of Agriculture for the illustra- 

 tions on pages 7, 8, 74, 77, 84, 87, 92, 96, 102, 127, 164, 169, 

 173, 191, 194, 196, 251, 254, 352, 357, 360, 363, 367, 378, 

 379, 388, 391, 398, 399, 404, 406, 412, 432, 434, 436, 437, 

 445, 450, 476; the Poultry Department of the Massachu- 

 setts College of Agriculture, pages 440, 445, 447; the 

 Kansas State College of Agriculture, page 3 ; the Alabama 

 Polytechnic Institute, page 115; the Washington State Col- 

 lege of Agriculture, page 421 ; the Iowa State College of 

 Agriculture and Mechanic Arts, pages 10, 15, 167, 184, 322; 

 the College of Agriculture of the Illinois State University, 

 pages 310, 317, 401, 403; the College of Agriculture of the 

 State University of Minnesota, pages 430, 453 ; the College 

 of Agriculture of the University of Ohio, page 173 ; the 

 Yakima Commercial Club of the State of Washington, 

 pages 99, 347, 419; the Crop Improvements Committee, 

 Board of Trade Building, Chicago, page 10; Wallace's 

 Farmer, Des Moines, Iowa, page 472; the Agricultural 

 Department of the International Harvester Company of 

 Chicago, pages 77, 99, 179, 181, 186, 188, 201 ; the James 

 Manufacturing Company, Fort Atkinson, Wisconsin, pages 

 317, 320, 490; the DeLaval Separator Company of New 

 York City, page 4-63 ; the Lehigh Portland Cement Com- 

 pany of Chicago, page 507; the Northern Pacific Railway, 

 page 424; and the David McKay Publishers, Washington 

 Square, Philadelphia, Pa., pages 492, 493. 



