BULLETIN 



The New York Botanical Garden 



A Biologic and Taxonomic Study of the Genus 

 Gymnosporangium 



By Frank Dunn Kern 

 CONTENTS 



Prefatory Note 



Part I. Biology of the Genus Gymnosporangium 



1. Introduction 



Life-History 



Comparison with other rust-genera 



Nuclear history 



2. Distribution and Relationships 



Problems 



General discussion of the data of distribution 



Relationships between the antithetic hosts of heteroecious speck 

 Factors affecting the distribution of Gymnosporangium 



3. Experimental Investigations of Life-Histories 



History 



Necessity of cultures 



Culture methods 



Collection and care of culture material 



Author's experimental work 



Summary of original cultures 



Unattached forms 



Clues of relationship 



Development of the telial stage 



Pathologic effects 



Economic importance 421 



Control 423 



