^ j g ON A NEW CANKER-DISEASE OF PRUNUS YEDOF.NSIS. etc. 
CONTENTS 
Pa<;e. 
1. Introduction 257 
2. Historical Review of Valsa-Diseases 258 
3. Symptoms of the Disease 259 
a. General Appearance of the Diseased Trees 259 
b. Appearance of the Diseased Portions of the Bark 260 
c. Development of the Canker 262 
d. Age and Parts of the Hosts affected 262 
4. Host-Plants 263 
5. Distribution of the Disease and Extent of the Damage 264 
6. Morphology of the Causal Fungus 265 
a. Stromata 265 
b. Pycnidia and Pycnospores 267 
c. Perithecia 269 
d. Asci and Ascospores 269 
e. Mycelium * 270 
7. Cultural Studies of the Causal Fungus 271 
a. Isolation 271 
b. General Cultural Characters 271 
c. Cultural Characters on Different Media 272 
8. Effects of Tannic Acid on the Causal Fungus 277 
a. Tannin and its Relationship to Fungi 277 
b. Tannic Acid Cultures 279 
Experiments. I — III 279 
c. Conclusion 285 
9. Confirmation of the Genetic Relation between Pycno- and Asco- 
sporous Stages 288 
10. Drop-Cultures 288 
a. Germination of Pycnospores 288 
b. Germination of Ascospores 290 
