Bui. 212, U. S. Dept. of Agriculture. 



Plate I. 



Fig. 1.— A 6-Year-0ld Jack Pine In- 

 fected WITH PERIDERMIUM CEREBRUM. 



The complete girdling of the main stem by 

 two oppositely arranged galls is shown. 

 Note the wedge-shaped gall tissues. 



Fiq. 2.— Four-Year-Old Seedlings 

 of Jack Pine, Showing the Char- 

 acteristic Swellings of Perider- 

 mium Cerebrum. 



The entire crown of the seedlings develops 

 into spherical brooms. 



Fig. 3.— Various Types of Infection of Young Jack Pine by Peri- 

 dermium comptoniae. 



Note that in the central figure the fungus has invaded the underground tissues 

 of the stem. 



