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Illinois Natural History Survey Bulletin 



Vol. 23. Art. 4 



veinal tissues within 6 hours. In the same 

 test, leaf curling or an early stage of wilt 

 developed within 22 hours. This browning 

 and curling occurred during clear weather 

 in August. With most of the materials 



listed in table 3, browning of interveinal 

 tissues developed in 8 to 36 hours ; leaf curl 

 and wilt developed in 22 to 70 hours. 



These tests show that toxic materials 

 in the abnormal sap that accumulates in 



Table 3. — Results of toxicity tests with sap from infected wood of wetwood-affected elms; 

 sap tested for toxicity on 2-year-old greenhouse-grown elm seedlings. Most tests terminated 

 at the end of 5 days. 



*Staled medium is a medium in which bacteria have been grown for some time. 



