482 



SPECIAL PLANT PATHOLOGY 





Fig. 167. — Disease of ash caused by Fames (Polyporus) fraxinophilus. i, Cross- 

 section of ash wood; 2, of medullary ray; 3, medullary ray, showing later stage of 

 attack; 4, 5, of wood cells; 6, starch grains from medullary ray cell; 7 diseased 

 wood; 8, transection from entirely rotted wood. (After von Schrenk, Hermann, 

 Bull. 32, U. S. Bureau of Plant Industry, 1903) 



