122 ILLINOIS ACADEMY OF SCIBNCE 
he assumes full responsibility for certain portions of the paper 
that are not entirely in accord with the views of these dis- 
tinguished critics. 
LOCAL INCLUSIONS OF PRAIRIE WITHIN FOREST 
ArTHUR G. VESTAL, Eastern ILLiINois State Normat SCHOOL, 
CHARLESTON 
The accounts of early settlement in Illinois and neighboring 
states mention frequently the occurrence of small openings or 
glades in the forest, covered with prairie vegetation. Probably 
most of them were small patches of upland prairie, surrounded 
by xerophytic oak forest which had slowly spread from nearby 
stream valleys. These small prairies, and most of the forest 
which surrounded them, are now destroyed by cultivation. But 
there may also have been prairie openings of a second type, 
which because of their small size and scattered distribution, 
have escaped notice, and are practically unknown today, 
although they are still fairly numerous. Probably they would 
be regarded as mere open places in the woods, without being 
recognized as prairie. These small prairie inclusions were 
first noted in 1916 in the neighborhood of Charleston. It is 
generally known that at the present time forest tends to en- 
croach upon treeless areas where cultivation does not prevent, 
but it is not generally known that in many places local excep- 
tions to this tendency may be found. Probably the greatest 
interest which these prairie inclusions may claim lies in the 
fact that many of them seem to be holding their own against 
forest invasion, and that in places prairie vegetation has even 
replaced forest, in recent years. . 
The commonest topographic site for these small areas of 
prairie is the windward crest of a valley or ravine running 
down to the east, southeast, or south, and the side-slope be- 
neath which accordingly faces to the south, southwest, or west. 
The essential condition is the great insolation and exposure to 
the dry summer winds from the south and southwest, making 
for local xerophytism. This is apparently a static rather than 
a dynamic feature of the environment, since both habitat and 
