THE EOTS OF WESTEKN WHITE PINE. 15 
for the bottom sites. This is due principally to the larger number of 
basal fire scars recorded for the trees on the slopes. On both types 
of site a steady increase of the total number of trees with injuries is 
recorded, ranging on the bottom sites from in the 41 to 60 age class 
to 97 per cent in the 201+ class. On the slope sites the percentage 
ranges from in the 41 to 60 age class to 99 per cent in the 201+ 
class. Comparing the entire stand of each type of site it is seen that 
the percentage of total trees infected is 55 on the bottom sites and 
55.3 on the slope sites. A more correct comparison of the amount of 
injury found in the stands of each type of site is made by con- 
trasting the percentages of total trees, both sound and infected, bear- 
ing injuries. For the bottom sites this percentage is 90 and for the 
slope sites TO, indicating that a larger number of trees on the bottom 
sites bore injuries. This difference may be partly due to the presence 
of a larger number of branch stubs on the trees of the bottom sites. 
These data clearly indicate the increasing danger of infection through 
injuries with the increase in age for both sites. 
From a study of Table V it appears that frost cracks as sources of 
infection are more common in the older age classes and not present 
at all in the younger. The recorded field data show that frost cracks 
were more frequent in the older trees, which accounts for the pre- 
ceding statement. 
The degree of injury for the two types of site shows a fairly steady 
increase with increased age and a slight difference in degree of injury 
for the total stand of the two types of site. The bottom sites have 
but a few tenths greater degree of injury. 
Table V shows that 10 to 30 per cent of the trees are without in- 
juries. These trees are principally in the youngest age classes and 
bear no dead branches. 
SPOROPHORES. 
Most of the sporophores encountered in the western white-pine study 
were those of Trametes pint. Very few sporophores of Poly poms 
schweinitzii or of Fomes dnnosus were found attached to the trees. 
Most of the Polyp orm schweinitzii fruiting bodies developed on the 
ground at the base or near the host, and the logging operations 
nearly always disturbed these from their original positions. A very 
few sporophores of Polyporus schweinitzii were found attached di- 
rectly to the base of the tree. The data in Table VI, therefore, are 
principally from field notes on one fungus, Trametes pmi. In this 
table it will be noted that the 41 to 60 age class is omitted, since no 
rot and therefore no sporophores were present on the trees of this 
class. On the bottom sites out of a total of 533 trees approximately 
30 per cent were found bearing sporophores. On these sporophore- 
bearing trees a total of 604 sporophores were recorded, of which 561, 
