INTRODUCTION ix 



Illinois State Teachers College; Clarence E. Taft, The Ohio State 

 University; Hiram Thut, Eastern Illinois State Teachers Col- 

 lege; L. H. Tiffany, Northwestern University; and Larry Whit- 

 ford, Agricultural and Technical College of North Carolina. 



In checking the descriptions, keys, and references, I had the 

 assistance of Mrs. Maynard Hale and Mrs. Robert Sigafoos. They 

 added much to the accuracy of the text, the indexing, and the 

 uniformity of the references. Professor John L. Blum of Canisius 

 College, Buffalo, copied or adapted many of the published figures 

 and added many new figures and details of spore walls. Without 

 his help the publication would have been greatly delayed. I am 

 grateful to each of these associates for their contributions to the 

 usableness of the keys. 



The Graduate School of The Ohio State University has aided 

 in the editorial work, and in the preparation of the figures and 

 plates. It is a pleasure to acknowledge this financial assistance. 



No attempt has been made to draw the figures to a certain 

 scale of magnification. Since the descriptions give the dimensions, 

 the principal value of the illustrations is the form of the various 

 structures associated with reproduction and the details of spore- 

 wall markings. The 789 figures illustrate 534 species, and all of 

 the known types of gametangia and spores. 



E.N.T. 

 Columbus, Ohio 

 1950 



