BIOLOGICAL PAPERS 



129 



The stations were numbered arbitrarily, number one being located 

 in the depression, numbers two and three in the ungrazed forest, 

 and number four in a portion of the forest which had been grazed. 

 The forest is here largely composed of white oak (Qiiercus 

 alba) and red oak (O. rubra), with occasional trees of the bur 

 oak ( O. inacrocarpa), shag-bark hickory (Carya ovata) and the 

 bitternut hickory (C. cordiformis) . Station four was almost 

 devoid of undergrowth, but at stations two and three there were 

 seedlings of the trees, particularly of the white oak, together with 

 a considerable amount of the hazel (Corylus americana) and a 

 few other shrubs. The instruments were placed in spots with 

 an average amount of shelter from both the trees and the shrubs. 

 The forest about station one had, in addition to the species 

 already enumerated, trees and seedlings of the white ash (Frax- 

 i}uis americana) and of black walnut (Juglans nigra.) 



An examination of the evaporation records shows that the 

 evaporating power of the air was highest during the month of 



Figure 1. Graph representing the evaporating power of the air 

 in a depression in the oak-hickory forest. 



