UNITED STATES DEPARTMENT OF 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, 1 Forest Pathologist, Office of Investigations in Forest 
Pathology. 
CONTENTS. 
Page. 
Introduction 1 
Basidiospores 4 
Sources of basidiospore ma- 
terial 4 
Methods used in the basidio- 
spore studies 5 
Germination of the basidio- 
spores 5 
Retention of the viability of 
the basidiospores 11 
Observations on the casting of 
the basidiospores 14 
Observations on the dissemina- 
tion of the basidiospores of 
Trametes serialis 10 
Mycelium _: : 19 
Preparation of cultures 19 
Macroscopic appearance of cul- 
tures grown at room tem- 
perature 19 
Microscopic characters of the 
mycelia on malt agar 22 
Page. 
Mycelium — Continued. 
Differentiation of the cultures 
upon agar 24 
Effect of temperature on the 
growth of the mycelium 2."> 
Secondary spores 2<; 
Intramural dissemination of 
fungi causing decay 2(i 
Review of the literature of 
secondary spore formation 27 
Occurrence of the secondary spores 
in cultures of the fungi studied 30 
Germination studies of the second- 
ary spores 32 
Experiments upon the dissemination 
of the oidia of Lenzites sepia ria 30 
Occurrence in buildings of the 
secondary spores of the fungi 
studied ;;x 
Summary sy 
Literature cited 42 
INTRODUCTION. 
There is no means of estimating the total annual loss occasioned 
by fungi which attack timbers in buildings, but from the evidence at 
hand it is certain that this loss is very large. This is particularly true 
in textile mills, paper mills, and canning factories, in which high 
x The writer wishes to acknowledge his indebtedness in connection with these studies 
to Prof. L. R. Jones, of the department of plant pathology of the University of Wis- 
consin, for his interest, encouragement, and criticisms; to Mr. C. J. Humphrey, of the 
Office of Investigations in Forest Pathology, Bureau of Plant Industry, Madison, Wis., 
under whose immediate direction this work was undertaken, for general supervision, 
facilities, and criticisms ; and to Mr. F. J. Hoxie, engineer and special inspector for the 
Associated Factory Mutual Fire Insurance Companies of Boston, Mass., for courtesies 
tendered in connection with mill investigations and for the loan of photographs. 
82278—22 1 
