254 BOTANICAL GAZETTE [October 



the tendency is toward the more complex methods, especially if 

 Pestalozzia be regarded as belonging to the Sphaeropsidales. As 

 was to be expected, in the pycnidial development no sexual organs, 

 ascogenous hyphae, or nuclear fusions were observed. 



Summary 



1. Pycnidia originate and develop by 2 main methods, namely, 

 meristogenous and symphogenous. 



2. The meristogenous method resolves itself into 2 modes, 

 simple and compound. 



3. Variations of the meristogenous method are found, for 

 example, in Coniothyrium pyriana and Sphaeronaemella fragariae. 



4. The symphogenous method is less often found and is variable. 



5. Acervuli arise in the same manner as do pycnidia, simple 

 acervuli by the simple meristogenous mode, and complex ones 

 usually by the compound meristogenous or symphogenous method. 



6. Complex subicles usually arise symphogenously, although 

 they may arise by the compound meristogenous mode. 



7. Simple sporodochia, especially those appearing on single 

 isolated strands, originate by the simple meristogenous method. 



8. Complex sporodochia, with a large base or subicle, usually 

 arise either by the compound meristogenous mode or symphoge- 

 nously. 



9. The pseudo-acervulus of the species of Pestalozzia studied 

 arises and develops as a pycnidium which breaks open and appears 

 like an acervulus. 



10. The simple meristogenous development is the more often 

 found in the Sphaeropsidales, while the compound meristogenous 

 and symphogenous modes are the more usual in the Melanconiales 

 and Tuberculariaceae. 



I gratefully acknowledge the very helpful guidance of Dr. F. L. 

 Stevens throughout the preparation of this thesis, and I also 

 wish to express my appreciation of suggestions and encouragement 

 by Professor William Trelease. Thanks are also due others 

 who have kindly furnished material or suggestions. 



University of Illinois 

 Urbana, III. 



