THE AGRICULTUEAL GRASSES OF THE UNITED STATES. 129 



The great variation in composition of gTasses becomes apparent on 

 examining the one hundred and thirty-six analyses; and by selecting 

 the highest and lowest determinations the following table of extremes 

 has been prepared : 



Liiyiifs of composition of grasses. 



Dtt substance. 



Highest. 



Lowest. 



19.24 



3.57 



5.77 



1.48 



66.01 



34.01 



37. 72 



17.68 



23.13 



2.80 



3.70 



.45 



1.6i 



.00 



60.7 



.00 



76.50 



60.00 



Ash 



Fat 



2^itrogen free extract 



Cmde liber 



Albuminoids 



Nitrogen 



2^ on-albaminoid nitrogen 



Per cent, of nitrogen as non-albuminoid 

 Water in fresh grass 



The highest ash is undoubtedly owing to the presence of adherent 

 soil, and the lowest carbo-hydrates are dependent relatively on the same 

 cause. The wide variations in fiber and albuminoids must be regarded, 

 however, as being entirely due to physiological causes, which are 

 ditficult to explain. Digitaria sanguinale, for instance, which in one 

 .specimen contains the extreme amount of albuminoids and a small 

 amount of liber has in another only half as much albumen and one and 

 three-quarter times as much fiber. We learn, then, that species are not 

 in themselves at all fixed in their compo.sition, there being as large vari- 

 ations among specimens of the same as between specimens of diflerent 

 species. Examples may be found in several portions of the precediuo- 

 tables, and, for illustration, .several analyses of Fhelum pratense and of 

 DactyJis glomeraia from widely separated localities are given in the fol- 



lowing table.* 



Analyses of PhJeum pratense (timothy) from various localities. 

 FULL BLOOM. 



Localitv. ~ z X 2 - 



Department garden, 1881 7. 16 4. 47 



Depanmtnt garden. ISSO 5.66 3.58 



MarvlaDd.... 4.93 4.22 



Xew Hampshire \.. 4.57 4.20 



Indiana 7,05 2.18 



50.03 

 58.93 

 52. 83 

 57.16 

 52.99 



27.35 

 21.93 

 30. 43 



28.28 

 32.26 



10.99 



9. 9U 



5.79 

 5.52 



H ^^ ' 



1.75 

 1.58 

 1.23 



29.1 

 24.0 

 12.2 



10.8 

 .0 



2218 GR- 



