50 



N. 



H. EXPERIMENT STATION [Bulletin 281 



u 



a 



s § 



■a 

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B 



'5 







O 



o 



s 

 o 









O CO c 1 - 



o'ci 



oo 



oo 



OCD 







p 



n 



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CO Irt -r 50 



OL.C 



o«o oco 



IfO OS 10 lO 



c-' ■»*♦ CO ■^' 



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 ot- 



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