ACKNOWLEDGMENTS 



The authors gratefully acknowledge permissions granted to 

 reproduce illustrations appearing in this book, as follows: 



Color plates I and II and Figures 7-2, 8-1, 8-2, 8-3, 8-4, 

 8-5, 15-9, and 15-10 reproduced from Hunger Signs in 

 Crops, revised edition, i)ublished by the American Society 

 of Agronomy and The National Fertilizer Association, 

 Washington, D. C, 1949. 



Color plate III reproduced from Clinical Nutrition, by 

 JoUiffe, Tisdall, and Cannon and published by Paul B. 

 Hoeber, Inc., New York, 1950. 



Color plate IV reproduced from Crystalline Vitainin Bj^ 

 U.S.P., published by Merck & Co., Inc., Rahway, N. J., 

 1951. 



