BIG SPRING PRAIRIE. 5 
eastern prairie is only an intermediate formation be- 
tween the marsh and the forest formation. Itis simply 
a question of time. ‘The observed facts corroborate this. 
As it is difficult adequately to define tree, but much 
easier to define deciduous tree, still easier to define 
Cottonwood tree, and easiest to define Populus grandi- 
dentata; so it is difficult to announce principles, or 
elaborate a statement of facts which shall fully apply to 
all prairies in all conceivable localities, and under their 
various natural conditions, but easier to apply the same 
to the eastern prairie, still easier to the Ohio prairie, 
and easiest to apply certain well-defined principles, and 
give a statement of observed facts in regard to Big 
Spring Prairie. The last named task shall be ours 
chiefly in the following article. In accordance with 
the above, our investigations have been conducted 
along the following lines. 
(1) Geological formations surrounding prairie, and 
the characteristic vegetation of same. 
(2) Past condition of prairie, especially since 1832, in 
which year the Big Spring Indian Reservation was 
thrown open to settlement. 
(3) The drainage of prairie, past and present, and its 
effect upon general level of same and also upon the 
character of the vegetation. 
(4) The lagging behind of effects, as shown by the 
observed facts that plants cling for a time to a local- 
ity after the conditions have changed, in this instance 
from the hydrophytic to the mesophytic. 
(5) The nature of the soil in the various portions and 
the characteristic vegetation of same. 
(6) ‘Tree introduction or encroachment upon prairie, 
the order and cause. 
(7) The prairie under cultivation. 
