1919] Fernald,— Ranges of Pinus and Thuja 47 
of banksian pine" and the country which is a “sandy flat, gradually 
rises southward for five or six miles, then it sharply rises to a ridge 
of gravel and boulders [gneiss]" (McInnes, n. s. xvi. 155A). Simi- 
larly in other regions of the upper Severn where “the whole area is 
occupied by rocks of Archaean age" (Camsell, n. s. xvi. 147A) " bank- 
sian pine and birch are found everywhere over the whole district" 
(Camsell, l. e. 151A); and so on through many other reports. 
Hutchinson finds the range of Pinus Banksiana “irregular” because 
“Tt is practically eliminated from the low lying lands to the south 
and west of Hudson Bay and James Bay,” naively adding, “water 
being the limiting factor.” When, however, we look into the lithol- 
ogy of the “low lying lands to the south and west of Hudson Bay and 
James Bay” the remarkable regularity or consistency of the range of 
Pinus Banksiana is made apparent, for this vast region from which 
Pinus Banksiana is “eliminated” consists of Silurian and Devonian 
limestones. On the splendid Geological Map of North America, pub- 
lished in 1911 by the United States Geological Survey, this limestone 
region to the south and southwest of Hudson Bay is indicated as 
extending from Rupert Bay to the Churchill River, a distance (air 
line) of 850 miles, with a breadth at the southwest of more than 200 
miles. Yet Hutchinson, finding the Banksian Pine “practically 
eliminated" from this region but abundant on acid Labrador and 
there extending north to latitude 56° says that “water” is “the limit- 
ing factor”; and he fails to detect the real factor because at the very 
outset he had somehow got an idea that “Cow es has shown that the 
composition of the rock from which any soil may be derived seldom 
acts in a limiting capacity with respect to the species which that soil 
may support." 
And it is not merely Cowles who has thus argued, for this dogmatic 
assertion has been repeatedly made by other leading American ecolo- 
gists. We thus find Clements writing: “ Apart from the effect which 
excessive amounts of acids and salts may have in reducing the chresard, 
the chemical character of the soil is powerless to produce structural 
modification in the plant. Since Thurmann’s researches there has 
been no real support of the contention that the chemical properties 
of the soil, not its physical nature, are the decisive factors in the dis- 
tribution and adaptation of plants." 1 
1 Clements, Research Methods in Ecology, 80 (1905). 
