134 BOTANICAL GAZETTE [FEBRUARY 
in earlier times may have been rock pools. Turning to the trees, 
we find representatives of the three climax species and no others 
in this particular spot. There is thus no xerophytic forest stage 
here, although near by scattered individuals of Pinus Banksiana, 
Picea mariana, Populus tremuloides, and Thuja occidentalis were 
noted. Balsam, the most abundant tree of the climax forest, is 
even here the dominant species, and this is true of the rock shores 
in general. None of the trees have attained great age, 50 years 
being the average. The rate of growth was found to vary greatly, 
Fic. 27.—Shore of type C: limit of forest extension very high, due to exposure 
and smoothness of slope; note abrupt transition from bare shore to forest; one of the 
islands bounding Rock Harbor on the southeast. 
those happily situated in regard to soil, moisture, and competition 
having wider rings than the less favored ones. In the rather close 
group below the center of the quadrat, due to a crevice, suppression 
was already evident, a few individuals, most of them slightly older 
than the others, being large and well formed, while the rest were 
small and stunted. Occasional standing dead trunks and frequent 
decayed logs remained as evidence of former generations. 
C (fig. 22) represents the third type of shore, which is common 
along the most exposed portions of the southeast coast (fig. 27). 
The distinctive feature is the abruptness of the transition from 
