456 BROOKLYN BOTANIC GARDEN MEMOIRS 
Fic. 1. Showing growth of sunflowers surrounded by wire netting. Note 
difference in size of plants which have penetrated through the wire-mesh enclosure, 
a feature of common occurrence. 
METHODS 
In the study of the effects of contact of various materials with 
plants we employed several methods and the experiments were carried 
on under different conditions. With the exception of some of the 
earlier experiments which were made out-of-doors, most of them were 
