m^^: ' ^ 



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Plate XXIX. — Sections of Acer Negundo; Pit Canker on Apple Branch. 

 5, cut about 45 cm. above 4, Plate XXVIII, cleft extending through wood; 6, cut 

 about 15 cm. above 5, which is about 1 cm. above upper end of cleft in bark; 7, cut 

 3.2 cm. above 6, about 5 cm. below first crotches; 8, " pit canker " around hole 

 made by bark beetle (Scolytus) at base of twig on tree frozen artificially in 

 September, 1911. 



(Photographed in July, 1912.) 



