THE RED ROT OF CONIFERS 9 



lock, fir and larch, while in pine it grows only in the heart-wood. That 

 the latter is not always true is shown in Plate I of a cross section of 

 an eight-inch pine, in which it will be noticed that the destruction has 

 continued irregularly into the sap-wood. This specimen was taken 

 from a standing tree upon which a fruiting body was found. 



Figure 1. Part of stem of a pine bearing sporophore of Trametis 

 Pini (one half natural size) (After Hartig). 



Hartig (1) says the fungus cannot enter through old branches 

 naturally pruned. This point was investigated and it was found that 

 the tree forms a natural protection for itself. When the branch dies 

 the free exudation of pitch causes that part which lies adjacent to 

 the cambium, (the growing tissue just inside the bark), as well as 

 that inside the tree to become hardened and impenetrable. This con- 



