BIOLOGICAL PAPERS 



131 



highest rate of the series, having a midsummer maximum of 

 22.12 cc. per day, and a daily average of 12.74 cc. The minimum, 

 2.'j'j cc. per day, almost exactly coincides with that of the 

 ungrazed forest, 2.87 cc. daily. A comparison of the two graphs 

 (Fig. 2) will show that the least divergence in the evaporation 



Figure 2. Graphs representing the range of the evaporating power 

 of the air in (a) the grazed and (b) in the undisturbed portion of the 

 oak-hickorv forest. 



rates of the grazed and ungrazed portions of the forest occurred 

 in the spring and autumn, when the trees were in a more or less 

 leafless condition. 



A comparison of these records with those obtained by Fuller,^ 

 in 1910, in related forest associations is most interesting and 



