124 THE AGRICULTURAL GRASSES OF THE UNITED STATES. 



The specimens, it will be seen, are from all parts of the conntrj^ aud 

 grown under every condition of soil and environment. Those collected 

 by Dr. Peter Collier in 1878 and 1879 were mostly from the poorer soils 

 and were intended to represent the wild grasses of the country. Those 

 collected in subsequent years by myself were chiefly cultivated varie- 

 ties. The development in nearly every case was full bloom or shortly 

 after, that being the period at which the grasses as a whole seem to be 

 cut for hay. 



The analyses have been calculated for '' dry substance" and also for 

 '' fresh grass" where the amount of water in the fresh grass had been 

 determined, otherwise for the average amount of water in hay as given 

 by Wolff. This figure is probably too high for the United States owing 

 to our drier climate, but, in the absence of exact data for the selection 

 of a more accurate one, it has been provisionally accepted. It is very 

 easily to calculate from the composition of the dry substance what effect 

 the presence of any percentage of water would have on the absolute 

 amount of any constituent present in a given weight of grass. 



