664 Plain, Prairie, and Forest. [ November, 
The writer has taken the liberty of italicizing a few words in 
the last sentence quoted from Mr. Lesquereux,! in order that the 
reader may not fail to notice that there is an essential agreement 
between us on the main point, which is that of the fineness of 
the prairie soil. That is to say, the main point in the opinion of 
the writer, but apparently not in that of Mr. Lesquereux, for 
he says, in speaking of the absence of trees as being caused by 
the fineness of the soil, “ This explanation, I think, cannot satisfy 
the mind.” When, however, we seek in his chapter on the 
prairies for the essential thing which does bring the desired men- 
tal satisfaction, we do not find it clearly stated, unless it be in 
the following sentences: “It is easy to see why trees cannot 
grow on such kind of soil [namely, the prairie soil, as described 
above]. The germination of seeds of arborescent plants needs the 
free access of oxygen for its development; and the trees, espe- 
cially in their youth, absorb by the roots a great amount of air, 
and demand a solid point of attachment to fix themselves. 
Moreover, the acid of this kind of soil, by its particularly anti- 
septic property, promotes the vegetation of a peculiar group of 
plants, mostly herbaceous.” That is to say, the soil formed by 
the decomposition of aquatic plants is unfavorable to the growth 
of forests, not only on account of its fineness, which must cer- 
tainly at least assist in preventing “ the free access of oxygen,” 
but also because its chemical qualities are such as especially 
favor herbaceous vegetation. 
That some portions of the prairie soil may have been formed 
by the decomposition of aquatic plants in the manner suggested 
by Mr. Lesquereux we are not disposed to deny, although not 
aware that it has yet been proved by chemical investigation that 
such a soil is chemically unfitted to support the growth of forest 
trees. We are, however, still disposed to adhere to the state- 
ment made in the Wisconsin report (1862), that “ the great mass 
of superficial clay, loam, and other loose materials lying on the 
solid rock in this region [the Lead Region of the Upper Missis- 
sippi,,a prairie country] is simply the residuum left after the 
more or less complete solution and removal of the soluble por- 
tion of the rock.”? That the prairie soil proper is not, as ; 
general rule, or necessarily, a soil containing a large amount 0 
1 Geology of Illinois (1866) vol. i, chap. vii., Onthe Origin and Formation of the 
Prairies, 
? See Wisconsin Report, chapter iii., on the Physical Geography and Surface Ge 
ology of the Upper Mississippi Lead Region, by the author of the present article, 
