- 26 - 
aggressiveness in reproduction, tolerance of shade, rate 
of growth, form, size, longevity, and resistance to injury 
and disease. The first question seems to he answered hy a 
consideration of the physical factors of moisture and light. 
Soil evidently has little to do with it; if all the hem¬ 
locks were removed from the north slope, maple oould easily 
take possession, as is evident from its regeneration in 
windfalls, and its prominence in the ranges further south. 
Hemlock, rather than maple, is thus the critical tree on the 
north side of the first range. This species is known to 
prefer cool, moist slopes, where the drainage is f&ir. Good 
drainage, however, may he left out of consideration here, 
as it occurs on the ranges farther south where hemlock is 
not prominent. The greatest humidity lies low along the lake 
shore. Here dense fogs are frequent even in the earlier part 
of the growing season. The smaller ratio of humidity at 
the higher elevations allows a corresponding increase in the 
intensity of the light near the top of the ridge. As before 
noted, hemlock is known to he very sensitive in its response 
to light; it is also known to he more shade tolerant than 
maple. Thus it seems clear that the dominance of hemlock 
at lower elevations on the north slope, and its absence as 
a dense stand on higher elevations and on the ranges further 
south, is correlated with the physical factors of moisture 
