344 



The Ohio Naturalist. 



[Vol. VIII, No. 7, 



canadensis, etc., a few small oaks, and Acer rubrum as the dom- 

 inant form. An interesting comparison is afforded when we 

 note that the country surrounding the lake and especially the 

 northern shore near the bog-island supports at various places 

 a forest vegetation in the form of woodlots. The most common 

 trees are the beech, elm, maple, oak, chestnut and walnut, — 

 examples of a temporary mesophytic climate society. 



In determining the influence on annual accretion of wood the 

 stumps of red maple were selected. A number of these trees 

 had been just recently felled both in the bog and on the shores near 

 by. It seemed desirable therefore to procure and record data 

 on measurements from such trees of the two conditions of hab- 

 itat, as were nearly the same in size, age, uniformty concentric 

 growth of wood, and general environment. The general climate 

 is assumed to be almost identical for both places, and being thus 

 eliminated, it became more easy to determine the effect of 

 edaphic conditions upon the rate of diameter growth of the species. 



From the number of trees at disposal five were selected from 

 the marginal bog-zone, and three were chosen from the wood- 

 lots near the shore. It may be objected that not enough trees 

 were analyzed to permit the conclusion drawn. In order to 

 eliminate sources of error, measurements were made, indeed, on 

 a larger number of sample trees. To the writer, however, it 

 seemed that the degree of confidence and the accuracy of the 

 statistical result depended not so much upon numbers, as upon 

 the functional criteria of the environment. It was not so much 

 the object of this study to establish variability, as to find a 

 suitable method of determining the influence of various factors 

 in the environment. A method was sought by which temper- 

 ature, light, humidity and soil data could be combined in a 

 single number. The fact that so large a part of plant activities 

 and adaptation is directly or indirectly connected with climatic 

 and edaphic factors, suggested that if a comparative and statis- 

 tical study of secondary growth on similar trees of various pro- 

 nounced habitats were made, a new basis for determining climatic 

 and edaphic regions of optimum development would be at hand. 



Put in tabular form the results of the measurements are as 

 follows : 



