112 



JOURNAL OF THE 



[October, 



process of natural pruning takes place, and as a result those 

 trees have tall branchless trunks, to the head of the tree. 



From the above we can understand what is shown to have 

 taken place in the specimens of wood before us. 



Fig. I is a representative of the tangential section of Yellow 

 Pine, enlarged to i^ diameters, showing the elliptically wound 



Fig. 2. 



tracheids, which have formed in the axilla of the dead branch. 

 Fig. 2 shows a portion of the same tracheids, enlarged to 15 

 diameters. 



Figs. 3 and 4 show similarly wound tracheids from the White 

 edar. Fig. 3 is enlarged to i^ diameters and Fig. 4 to 15 

 diameters. 



As soon as the lower branches die, the tree not only makes 

 strenuous efforts to protect itself from the attacks of fungi 



