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J. E. WEAVER 



usually assigned to only one or two quadrats. This leaves time 

 for a general survey of the field. After the quadrating has been 

 accurately accomplished they are furnished with the records of 

 preceding years and are required to give a discussion at some 

 future time of the movements of the vegetation. Not infre- 

 quently after such class discussion students voluntarily revisit 

 the field for further data. 



Fig. 6. Quadrats 1 and 2 plotted in October, 1916 (left), 1917, and 1918 

 repectively. A = Atriplex hastata, 'D = Dondia depressa, T)\ = Distichlis spicata, 

 X = rhizomes of Distichlis, Il = Hordeum jubatum, !* = Polygonum aviculare 

 11 = Rumex allissiwMm. 



ILLUSTRATIVE EXPERIMENTS IN THE PRAIRIE 



Rather large tracts of native grassland undisturbed except by 

 mowing are still to be seen in eastern Nebraska. During the 

 past few years a small area of high prairie has been set aside 

 for investigational purposes. This is undisturbed except for 

 denuded quadrats, planted quadrats, bisects, etc. (24). A knoll 

 in this high prairie is underlaid with a glacial deposit of coarse 



