March,. 1912.] THE CHESTNUT BARK DISEASE. 



219 



GXPLA/VATtON'i 



A// -frees c/eod 

 A //trees diseased 

 Loco/ d/seasec/ areas 

 f Former d/s eased '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. 



