March, 1912.] THE* CHESTNUT BARK DISEASE. 



219 



FX PL A /VA Tl ON : 



i All frees c/eod 

 A //Trees diseased 

 L oca/ diseased areas 

 Former diseased areas 



FIG. 10. Map showing distribution of diseased chestnut. The area of gen- 

 eral infection in Pennsylvania is much greater than would be indicated by 

 this map. 



