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negligible. The isolated prairie groves described in an earlier 

 paper are all open to the east, but they have persisted because 

 of their western protection by sloughs. 



But the fires coming from the west have made a great effect 

 upon the forests, and indirectly upon the soil as well. They have 

 in some cases completely cut off portions of the forest from the 

 main bodies with which they were formerly connected, producing 

 thereby isolated groves. A second effect is seen in the exemption 

 of certain portions of the prairie from fires, upon which habitats 

 forests have developed after the introduction of fires. A third 

 effect is seen in the general restriction of forests on the west side 

 of streams to narrower belts than are found on the east side of the 

 same streams, and a fourth in the apparently complete removal 

 of thousands of acres of forest and its conversion into prairie. 

 These results of fires will be discussed in turn. 



I. Isolated prairie groves are of common occurrence in central 

 Illinois, and doubtless also in other parts of the Middle West. 

 The description of one such grove has already been cited. The 

 location of others may be determined by reference to county 

 histories, and more exactly by the original land surveys of the 

 various counties. These surveys, made between eighty and 

 ninety years ago, show the location of the forests with consider- 

 able accuracy, if at all, but in some counties no definite mention 

 of the forests is made, and in a few cases some of the groves have 

 been omitted. These are mostly of small size, and while of con- 

 siderable significance to the phytogeographer, were probably 

 not considered by the surveyor worthy of mention. 



Copies of the original surveys have been examined and trac- 

 ings made for eight adjacent counties in central Illinois, Cham- 

 paign, Coles, De Witt, Douglas, Macon, Moultrie, Piatt, and 

 Shelby. They indicate over twenty such isolated groves, of 

 various shapes and sizes, and located in various habitats. Every 

 one of these which has been visited by the writer, except two 

 referred to under the next general effect of fires, is in some way 

 connected with a stream or series of sloughs. Those which are 

 located along streams are probably remnants of a former con- 

 tinuous strip of forest which has been cut in sections by fire. In 



