PREFACE IX 



hoped that it will minimize misunderstandings in the interpretation of 

 species as described and understood by our predecessors. In addition, 

 it is intended as a guide by which the investigator may reach the accumu- 

 lated literature relative to the activities and signidcance of these molds. 



Although the plans for this book had long been tentatively formed, and 

 the materials partially segregated into fascicles, actual preparation fol- 

 lowed the suggestion of Dr. W. J. Robbins, then Chairman of the National 

 Science Fund, that help to speed up the completion of the book might be 

 found. In the Spring of 1945 the George F. Baker Charitable Trust Fund 

 made available to the National Science Fund a sum sufficient to provide 

 the services of professional, technical, and clerical personnel necessary 

 to carry out the work. Thereupon, a cooperative agreement was drawni up 

 between the Department of Agriculture and the National Science Fund and 

 work on the project was initiated in June 1945. The cooperation of the 

 Northern Regional Research Laboratory in providing the time of the 

 senior author, in supplying space and equipment, and in performing multi- 

 tudinous administrative details has been essential to the completion of 



the task. 



Since fully two thousand strains, in addition to our own original Collec- 

 tion of at least as many more, have been studied, it is impractical to 

 recognize here the contributions of the many workers who cooperated by 

 furnishing cultures. Acknowledgments are made in the text wherever 

 their organisms are discussed. 



In the preparation of this manuscript, and in the cultural studies upon 

 which it is largely based, important contributions have been by May H. 

 Flickinger and Jane A. Roberson who made cultures for examination and 

 prepared lyophilized preparations of the strains discussed in the text; by 

 Roland W. Haines and Robert E. Garrett, photographers at the Northern 

 Regional Research Laboratory, who made all of the color pictures as well 

 as the black and white photographs of plate cultures; and by Kathryn E. 

 Dore who typed the manuscript in its final form. 



The authors are indebted to the Chas. Pfizer & Co., Inc., Brooklyn, 

 New York, for underwriting the cost of reproducing the natural color 



photographs. 



Administratively, many individuals have contributed to the cooperative 

 project under which this manuscript was prepared. These include W. J. 

 Robbins and Harlow Shapley, Chairmen of the National Science Fund, 

 O. E. May and L. B. Howard, Chiefs of the Bureau of Agricultural Chem- 

 istry and Engineering, and H. T. Herrick and G. E. Hilbert, Directors 



of the Northern Regional Research Laboratory. 



The Authors. 



