302 JOURNAL OF FORESTRY 



in growing corn. Similarly it is pointed out later, with respect to 

 Ohio, that wheat is grown in the same region as corn largely because 

 it is a good complement to corn in rotation. 



Other well known facts of crop distribution are mentioned, but we 

 believe the forester will find greatest interest in tlie attempt to recon- 

 cile natural crop dominance with dominance as dictated by economics. 

 The importance of industrial centers, and the somewhat familiar idea 

 of rent circles about these centers, which determine the need for in- 

 tensive farming and hence the character of the successive, concentric 

 crop zones, are discussed. These ideas have been used in forest econ- 

 omics and are especially good ones for the ecologist to keep in mind. 



Part III, Crop Regions of Ohio, brings us still closer to the struggle 

 between natural or ecological factors and economics, for Ohio is a 

 State with many important cities. On the one hand the geology and 

 glacial history, topography and soils, climate, natural vegetation cen- 

 ters and crop centers are discussed in such a manner as to constitute 

 a very valuable monograph on the State. On the other hand, the 

 correlation which is shown between crop centers and natural vegeta- 

 tion centers or the factors which produced them, is somewhat vague, 

 possibly because of the economic factor. We believe the argument 

 might have been much more convincing had the available data by 

 counties been used, instead of dividing the State into four arbitrary 

 quadrants. It is to be regretted that more effort was not expended on 

 this chapter, and on detailed maps, and perhaps less on the general 

 discussions of the first section. 



As a closing argument there is given a discussion and two maps of 

 the land values of the State. The first map shows the relative land 

 values of the State for tax purposes, and the second the same data 

 •with the local influence of population centers eliminated as far as 

 possible. The second map, we should say, has real ecological sig- 

 nificance. Particularly are the land values influenced by the degree 

 of glaciation. The southernmost part of the State, which was never 

 covered by an ice sheet, has the lowest values, though receiving the 

 greatest precipitation, while the large area of highest values, con- 

 tiguous to Lake Erie, corresponds closely to the outline of the old 

 >dacial Lake Maumee, which persisted long enough to silt over the 

 glacial deposits. It is possible that some of this value, however, is 

 obtained indirectly, as through the advantage of commerce on the Lakes. 



Looking back from this point, it is seen that edaphic factors as 

 represented in land values or productive capacity have only a small 



