CONTENTS 



Page 



Acknowledgments 407 



Review of Literature 407 



Hosts and Distribution 408 



Trunk Pathology 409 



Wood Discoloration 409 



Gas 410 



Sap 410 



Root Pathology 413 



Branch Pathology 414 



Foliage Pathology 416 



Dissected Elm 417 



Isolations 418 



Histology 419 



The Wetwood Organism 420 



Morphology 420 



Cultural Characters 420 



Biochemical Reaction 422 



Taxonomy 422 



Erwin'ta nimipressuralis New Species 423 



Inoculations 423 



' American Elm, Greenhouse Inoculations 423 



I Siberian Elm, Greenhouse Inoculations 424 



Toxicity Tests for Wilt 425 



Laboratory Tests on Cut Shoots 425 



Field Tests on 2-Year-Old Elms 426 



Greenhouse Tests on 2-Year-Old Elms 427 



Greenhouse Tests on 7- to 12-Foot Elms 429 



Pressures in Affected Elms 430 



Field Studies 430 



Greenhouse Studies 433 



3as Analysis 436 



Sap Analysis 437 



The pH of Sap 438 



Control Studies 439 



Helione Injections and Feeding in 1940 439 



Urea Feeding in 1941-42 439 



Drains Installed in 1942 440 



Injections in 1941 and 1942 440 



VllSCELLANEOUS EXPERIMENTS 441 



Injections of Toxic and Stimulatory Materials 441 



Distribution of Malachite Green in Elms 441 



Soil Tests 443 



Elm Seeds 444 



Growth Associations 444 



onclusions 444 



nummary 445 



iterature Cited 446 



