UNITED STATES DEPARTMENT OP AGRICULTURE 
BULLETIN No. 1053 
Contribution from the Bureau of Plant Industry 
WM. A. TAYLOR, Chief 
Washington, D. C. 
PROFESSIONAL PAPER 
May, 1922 
STUDIES OF CERTAIN FUNGI OF 
ECONOMIC IMPORTANCE IN THE 
DECAY OF BUILDING TIMBERS 
WITH SPECIAL REFERENCE TO THE FACTORS 
WHICH FAVOR THEIR DEVELOPMENT 
AND DISSEMINATION 
By 
WALTER H. SNELL, Forest Pathologist 
Office of Investigations in Forest Pathology 
CONTENTS 
- Page 
Introduction 1 
Basidiospores 4 
Mycelium 19 
Secondary Spores 26 
Occurrence of the Secondary Spores in 
Cultures of the Fungi Studied 30 
Germination Studies of the Secondary 
Spores 32 
Experiments upon the Dissemination of 
the Oidia of Lenzites sepiaria 36 
Occurrence in Buildings of the Secondary 
Spores of the Fungi Studied 38 
Summary 38 
Literature Cited 42 
WASHINGTON 
GOVERNMENT PRINTING v OFFICB 
1922 
