INTRODUCTION 



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cytoplasm of the ascospore builds the endospore, the inner layer of the 

 spore wall. The spore nucleus may subsequently divide, usually followed 

 by septum formation, so that the ascospore may eventually be two-celled 



Fig. 66. Ascomyceteae. Variations in 

 ascospore number in asci of various 

 species. (A-C) Tuber candidum Hark. 

 1-spored, 2-spored, and 4-spored asci, re- 

 spectively. (D) Septotinia podophyllina 

 (E. & E.) Whetzel. 8-spored ascus. (E) 

 Dipodascus uninudeatus Biggs. Multi- 

 sporous ascus. (F) Thelebolus stercoreus 

 Tode ex Fr. Section through apothe- 

 cium showing the single ascus with 1000 

 or more ascospores. (A-C, after Gilkey: 

 Oregon State Monographs. Studies in 

 Botany, 1:1-63. D, after Whetzel: Myco- 

 logia, 29(1):128-146. E, after Biggs: My- 

 cologia, 29(l):34-44. F, after Ramlow: 

 Botan. Ztg., 64.(1) -.85-99.) 



or even multicellular, though perhaps the one-celled condition is the more 

 frequent, as it is probably the more primitive. (Fig. 66.) 



The ascus varies in shape from cylindrical or clavate in those forms 

 with a well-developed hymenium, to ovoid or subglobose in those in 

 which the asci are scattered or only loosely clustered. The ascospores 

 escape in various manners. In many cases, particularly in the forms with 



