PAPERS OX BIOLOGY AND AGRICULTURE 209 



The leaves of lot D are from a dood plain of the Des- 

 plaines river at Riverside, 111. The plot was about fif- 

 teen feet from the river and the soil was quite moist. 

 Other species growing in the same situation were : 



Quercus macrocarpa 

 Acer sacchariuum 

 Juglans nigra 

 Tilia americana 

 Ulmus americana 

 Ambrosia trifida 

 Crataegus 

 Panicum 



The leaves from which measurements were made were 

 growing in the shade of an elm tree. 



Lot E was located at the top of a dune at Mineral 

 Springs, Ind., a xerophytic dune environment. The other 

 species in the same environment were: 



Juniperus communis 

 Cornus stolouifera 

 Ehus aromatica 

 Vitus \-ulpina 



The plants were growing on bare sand, but were more 

 or less shaded. 



Lot G was located on a sandy level beside the tracks 

 at Smith. Ind. The soil, though sandy, had more humus 

 than either of the other dune locations. The other 

 species found there were : 



Populus deltoides 



Plantago 



Fragaria 



Salix (nigra) 



Grasses 



Compositae 



The situation seemed very xerophytic and the plants 

 were not as shaded as in the other three locations. 



From some of the leaves collected in the different 

 plots, blue prints were made in order to determine the 



