SCIENTIFIC PAPERS. 
A DISEASE OF TAXODIUM DISTICHUM KNOWN AS PECKI- 
NESS, ALSO A SIMILAR DISEASE OF LIBOCEDRUS DECUR- 
RENS KNOWN AS PIN-ROT.* 
BY HERMANN VON SCHRENK. 
INTRODUCTION. 
The diseases of forest trees had attracted attention for 
many years before any attempt was made to arrive at an 
understanding of their true nature. With the investigations 
of Th. Hartig,t Schacht,} and Willkomm,§ a beginning was 
made, but not until the epoch-making researches of R. 
Hartig,|| were some of the complex relations between 
‘diseased trees and the exciting causes made clear. In 
England, Marshall-Ward has paid some attention to the 
diseases of trees, but in this country few have given this 
subject much study. 
A tree may be diseased because of the natural decadence 
of its vital forces incident to old age, it may be influenced 
by abnormal physiological conditions, or its functions may 
be impaired by the activities of a disturbing organism. 
* A thesis presented to the Faculty of Washington University for the 
degree of Ph. D., April, 1899. 
+ Hartig, Th. Abhandlung iiber die Verwandlung der polycotyle- 
donischen Pflanzenzelle in Pilz u Schwammgebilde, u. die daraus 
hevorgehende Fiulniss des Holzes. 1833. 
t Schacht, Hermann. Der Baum, Studien tiber Bau u. Leben der 
hdheren Gewiichse. Berlin. 1860. 
§ Willkomm, M. Die mikroscopischen Feinde des Waldes. Dresden. 
1866. 
| Hartig,R. Wichtige Krankheiten der Waldbiume. Berlin. 1874.— 
Die Zersetzungserscheinungen des Holzes, etc. Berlin. 1878. 
Separates issued June 3, 1899. 1 
2 
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