PAPERS ON AGRICULTURE 91 



allowing for seasonal variations and fertility differences, 

 probably approximates the height of ear of the original stock. 

 The hybrid was reasonably uniform in respect to height of 

 ear, its coefficient of variability being intermediate between 

 those of the parents. In number of internodes below the ear 

 and average length of internode, the cross was intermediate 

 between the parents. The time required for maturity was 

 intermediate in the cross, although favoring the Low Ear par- 

 ent. In yield of grain, however, the cross gave an increase 

 of 37 per cent over the higher yielding parent and 27 per 

 cent over a nearby plot of Learning, the variety from which the 

 parents originated. It may be said then that in respect to 

 certain physical measurements, for which the two strains have 

 been divergently selected, the cross gives us values closely ap- 

 proximating the original variety, and in respect to yield the 

 vigor lost to some extent by close breeding is fully restored. 



EFFECT OF ALTITUDE UPON THE COMPOSITION 

 OF FORAGE PLANTS 



Henry G. Knight, University of Illinois 



There is little question that a knowledge of the effects of 

 altitude upon, the growth and composition of plants is impor- 

 tant not only from a scientific standpoint, but also for prac- 

 tical reasons. A better knowledge of these effects and the 

 primary causes which go to produce them will undoubtedly 

 throw some light upon our problems and help us to under- 

 stand better the effects of slight changes of altitude which 

 may be difficult to determine directly. Then, too, this sub- 

 ject is of special importance to those who are interested in 

 agricultural practice at the higher altitudes. 



Between the altitudes of 4,500 feet and 7,500 feet there are 

 three Agricultural Experiment Stations in the United States 

 — Utah Station at Logan, altitude 4,500 feet; Colorado Sta- 

 tion at Fort Collins, altitude 5.000 feet, and Wyoming Sta- 

 tion at Laramie, altitude 7,200 feet. The altitude of the last 

 named station is at about the limit of successful agriculture 

 for the latitude in which it is situated, but in the mountainous 

 sections of the world there are considerable areas of land in 



