94 



ILLINOIS ACADEMY OF SCIENCE 



Downy Oat Grass 10000 



Downy Oat Grass 11000 



Giant Sedge 9500 



Giant Sedge 10000 



Mountain Sedge 9500 



Mountain Sedge 10500 



Mountain Sedge 8000 



Mountain Sedge 10000 



Parry's Rush 9500 



Parry's Rush 10500 



Western Wheat Grass 4300 



Western Wheat Grass 7200 



Rough Hair Grass 8000 



Rough Hair Grass 10000 



Slough Grass 8000 



Slough Grass 8500 



1907 

 1907 

 1908 

 1908 

 1908 

 1908 

 1909 

 1909 

 1909 

 1909 

 1908 

 1908 

 1909 

 1909 

 1905 

 1905 



9.69 



12.20 



10.00 



11.76 



13.26 



15.76 



7.12 



12.37 



11.96 



16.75 



8.71 



10.92 



7.47 



9.87 



6.33 



7.54 



As a summary of forage during the years 1908, 1909 the 

 following table is given : 



TABLE III. 



No. of Samples 



Altitude 



N. X. 6.25 

 1908 



1909 



8.55 



8.97 

 10.40 



7.99 

 13.46 

 12.11 



The nitrogen content of the forage plants increases with 

 altitude. It was believed that this might be explained by dif- 

 ferences in soils, but investigations with this in view have 

 not thus far supported this theory. The other accepted fac- 

 tors such as light, heat, air and moisture have been given con- 

 sideration, but no one of them seems to afford an adequate ex- 

 planation, but the changes in the first four together are the 

 probable cause of the difference noted. Under the more ad- 

 verse conditions of the higher altitudes plants must in a 

 shorter time come to the fruiting period if the species are to 

 survive. Since seed require larger proportions of nitrogen 

 than the foliage, we would, since the weight of foliage be- 

 comes less, expect that a higher nitrogen content would be 

 found in the foliage of the plants at higher altitudes in prepar- 

 ation for the fruiting period. 



