1913] COOPER—ISLE ROYALE 17 
Returning to the trees, the first conclusion would naturally be 
that we have here a stage in the succession approaching but not 
having reached the final or climax condition. The spruces and 
birches appear like relicts, and the balsams, which seem to be of all 
ages, but mostly younger than the trees of other species, are appar- 
ently succeeding them. The seeming probability is that before 
long the birches and spruces will have died out, leaving a pure 
growth of balsam which in the future will succeed itself. Appear- 
ances of this kind have sometimes been considered sufficient to 
prove that succession is in active progress, and there are undoubt- 
edly many cases where the phenomena are not deceptive. In no 
case, however, should the mere appearance of rapid succession be 
admitted as valid evidence until verified by surer methods of study. 
The results of an attempt to use such methods are detailed in the 
two following sections. 
II. STUDIES OF INDIVIDUAL SPECIES 
ABIES BALSAMEA (balsam fir).—If it be objected that the forest 
is after all a practically pure stand of balsam, with a mere scatter- 
ing of other species, the following facts will be sufficient answer. 
It is true that in number of individuals, all sizes considered, the 
balsam is greatly preponderant. Of the 254 trees included in the 
six quadrats soon to be described, 78.7 per cent are balsam. But 
if we take account only of those trees which may be considered as 
forming the mature stand, the percentage of balsam becomes much 
smaller. Size, not age, is here the proper criterion. Considering 
those trees which are 1.25 dm. and more in diameter, which is a 
rather low limit to set, the proportion is only 56.7 percent. Among 
the larger trees the balsams are still less numerous, making only 
33-3 per cent of those 2.5 dm. and more in diameter (fig. 4). The 
same facts are shown when age is considered instead of size, though 
in a somewhat less striking manner (fig. 5). 
Two causes are responsible for the preponderance of balsam in 
the young growth. First, the seedlings make a successful start 
in almost any sort of situation, provided sufficient light be available. 
Very young seedlings were seen commonly in such diverse situa- 
tions as the following: natural openings in the forest caused by 
