124 



The specimens, it will be seen, are from all parts of the country and 

 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 

 varieties. 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 u 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 

 easy 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. 



