Acknowledgments 



It is through the courtesy of a number of individuals, corpora- 

 tions, and publishers that many of the illustrations are included 

 in this book. Specific acknowledgment is found in the legends 

 accompanying these figures. The editors of the Journal of Bac- 

 teriology, the Journal of Botany, the Journal of Experimental 

 Medicine, and the Journal of Infectious Diseases have been very 

 cooperative in allowing material to be reproduced from original 

 articles in their publications. Some of the prints are from the 

 collection of the Committee for Visual Education in Microbiology 

 of the Society of American Bacteriologists. 



Copyright owners, including Appleton-Century-Crofts, Inc., 

 Harper and Brothers, D. C. Heath and Company, McGraw-Hill 

 Book Company, Inc., C. V. Mosby Company, W. B. Saunders 

 Company, D. Van Nostrand Company, Inc., and John Wiley and 

 Sons, Inc., have given permission for the use of designated material 

 from books published by them. Their courtesy is appreciated. 



I am indebted to my colleague, Dr. Robert C. Cleverdon, for 

 his critical reading of the manuscript and for his invaluable sug- 

 gestions for improvement of the text. My thanks are extended to 

 Mrs. Gordon R. Hanks who typed and retyped the manuscript. 



And in conclusion, I acknowledge sincere gratitude to Dr. 

 Walter L. Kulp, Dr. Milton J. Foter, Mr. Vinton E. White, Miss 

 Christie J. Mason, Dr. Leo F. Rettger, Dr. George Valley, Dr. 

 George H. Smith, and Dr. Philip B. Cowles— my microbiology 

 teachers— for the foundation they have given me in this science. 

 viii 



