ACKNOWLEDGMENTS 



The author wishes to thank many friends and students who 

 have made suggestions regarding the book. Especially is he 

 under obligation to the following, who have critically read the 

 manuscript or the proofs : Dr. Harris M. Benedict, University of 

 Cincinnati; Dr. J. M. Lewis, University of Texas; Dr. Burton 

 E. Livingston, Johns Hopkins University ; Dr. S. O. Mast, Johns 

 Hopkins University; Dr. Charles A. Shull, University of Ken- 

 tucky; Dr. A. B. Stout, New York Botanical Garden; Dr. G. 

 H. Transeau, Columbus, Ohio ; to his colleagues at Ohio State 

 University, especially Dr. Jay B. Park, Dr. H. C. Sampson, 

 Dr. A. E. Waller, Professor W. G. Stover, and Mr. Paul Sears; 

 to Mr. G. W. Salisbury, Principal of Atchison County High 

 School, Effingham, Kansas; Mr. J. R. Locke and Miss Edith 

 E. Pettee, Highland Park High School, Detroit, Michigan ; Miss 

 Ella M. Bennett, High School, Ann Arbor, Michigan; Miss Lucy 

 M. Phelon, High School of Commerce, Springfield, Massachu- 

 setts ; Miss Ruth Jackson, High School, Wichita, Kansas ; and 

 Miss Maude Flynn, High School, Columbus, Ohio. 



