34 BOTANICAL GAZETTE [JANUARY 
indicated by double symbols. The absence of very young growth 
_is explained by the fact that the forest floor was covered by a thick 
mass of ground hemlock. 
' Black spruce and tamarack are found occasionally throughout 
the forest. Since they are both very intolerant of shade, they 
probably make a successful start only where an extensive windfall 
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Fic. 12.—Quadrat 5: size of trees; for explanation of symbols see fig. 10 
has let in abundant light. The black spruce as a member of the 
upland forest is abundant in one locality on the southeast shore 
of Isle Royale and in certain other places. The evidence seems tO 
show that this species in abundance in the upland forest indicates 
a transitional stage approaching the climax. The subject will be 
treated again in the consideration of the rock shore succession. 
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