RELATION BETWEEN EVAPORATION AND PLANT SUCCESSION 1 69 
ized in their distribution than pine or maple, which explains why 
Thuja was not found in some of the smaller bogs. Atmometers No. 39 
and No. 40 were run in a small Chamaedaphne bog in which Larix and 
Picea mariana were conspicuous invaders. This bog has been thor- 
oughly fireswept and no Thuja is present. Atmometers No. 41 and 
No. 42 were started by Thuja seedlings on the beach and at the edge 
of the beach thicket respectively, but after the first week had to be 
Fig. 7. A view in a hardwood area cut over in 1913-14, showing atmometer 
No. 5, The conspicuous weed is Erigeron canadensis. July 22, 1915. 
discontinued. In a small slashed bog along a little stream east of 
Douglas Lake, atmometers No. 37 and No. 38 were run in moderately 
open conditions near healthy Thuja seedlings. At East Point there 
are several bogs in different stages of development. Atmometer 
No. 27 was run near a Thuja seedling at the edge of the fringing dune, 
exposed to winds from the lake, No. 28 near Thuja seedlings at the 
inner edge of the bog, No. 29 in the densest part of the bog in which a 
Thuja seedling could be found growing, while No. 30 was run, in 
August, in the deepest and darkest spot which could be found. Thuja 
seeds but no Thuja seedlings were present. Atmometer No. 36 was 
run in a small bog in the aspens south of the Biological Station. 
Larix, Thuja and Picea were present, but fire had seriously damaged 
the vegetation. 
