PREFACE vii 
Mfg. Company, Southport, Conn., for illustration 
No. 28; to C. B. Sayre of Purdue University for illustra- 
tions Nos. 29, 68, 81, 1386, 187 and 138; to the Bureau of 
Plant Industry for illustrations Nos. 85 and 36; to the 
United States Department of Agriculture for illustration 
No. 39; to the Ohio Agricultural Experiment Station for 
illustration No. 53; to E. F. Stoddard of the Maryland 
Agricultural College for illustration No. 66; to the Ten- 
nessee Experiment Station for illustrations Nos. 76 and 
77; to Sutton and Sons of Reading, England, for illustra- 
tions Nos. 80, 92, 125 and 126; to G. L. Tiebout of the 
Louisiana College of Agriculture for illustration No. 84; 
to David Lumsden formerly of New Hampshire College, 
now of Cornell University, for illustrations Nos. 91, 95 and 
104; to L. M. Montgomery of Ohio State University for 
illustrations Nos. 127 and 129; to W. H. Weinschenk of 
New Castle for illustration No. 134; to the Virginia 
Truck Experiment Station for illustration No. 139; and 
to C. G. Woodbury of Purdue University for illustration 
No. 146. 
