PREFACE ix 



on the basis of the mode of spore -production and spore-discharge, 

 an attempt has been made to show that Sporobolomyces is to be 

 regarded as a basidiomycetous Yeast-genus. 



The second Chapter of Part II, of which A. H. R. Buller and 

 T. C. Vanterpool are joint authors, gives an account of the produc- 

 tion and violent discharge of the so-called secondary conidia of 

 Tilletia tritici. The authors regard these secondary conidia as the 

 true basidiospores which correspond to the similarly constructed 

 and similarly discharged basidiospores of the Hymenomycetes and 

 the Uredineae. 



In the final Chapter of Part II, the structure and mechanism 

 of the Sphaerobolus stellatus gun has been redescribed in detail. 

 Attention has been called to the fact that Sphaerobolus is copro- 

 philous as well as xylophilous, and the mode of dissemination of the 

 fungus has been discussed. 



This volume contains one hundred and seventy-four illustrations 

 in the text, including one hundred and thirty drawings and forty- 

 four photographs. Thirty-three of the drawings have been bor- 

 rowed from other authors. The other drawings were executed by 

 my own hand or in conjunction with Miss Ruth Macrae or T. C. 

 Vanterpool. For copying the drawings reproduced in Figs. 21 

 and 23 my thanks are due to Dr. Nellie Carter. The source of each 

 borrowed illustration is acknowledged in the text. 



Of the forty-four photographs in the text twenty-six were made 

 under my direction, and the others were kindly contributed by 

 friends and correspondents : one by Somerville Hastings, two by 

 H. T. Giissow, four by I. L. Conners, ten by Leva B. Walker, and 

 one by the Manitoba Department of Agriculture. 



My best thanks are due to the Canadian National Research 

 Council for grants in aid of the work. These grants have enabled 

 me to employ in succession three research assistants, Miss Ruth 

 Macrae, M.Sc. (McGill), Miss Eleanor S. Dowding, Ph.D. (Manitoba), 

 and C. C. Neufeld. The investigations on Sporobolomyces and 

 Sphaerobolus were accomplished in conjunction with Miss Macrae, 

 those on hyphal fusions and protoplasmic streaming in the Higher 

 Fungi in conjunction with Dr. Dowding, and those on protoplasmic 

 streaming in Rhizopus nigricans in conjunction with C. C. Neufeld, 



