Winifred E. Brenchley 157 



by water, where the air is naturally always moist even in hot weather, 

 while the dry harsher leaves of the spaced plants may well be correlated 

 with the relatively low humidity of the air with which they are sur- 

 rounded. The marked difference in humidity might not occur out of doors 

 where there is a freer circulation of air than in a greenhouse, and the 

 absence of this extra moisture when plants are crowded in the field may 

 account for the fact that the excessive leaf growth in barley under these 

 conditions is not a usual occurrence. The extra growth of the crowded 

 plants at this stage is not caused by a higher temperature among the 

 leaves, as almost every day the dry bulb in this position registered a 

 lower temperature than that exposed to the free air of the greenhouse. 



Table VIII. 



Difiference between humidity 

 of house and humidity among 



plants. Number of days difference 



Percentage of saturation was recorded 



Humidity among plants higher than humidity of house. 

 0—10 8 



11—20 8 



21—30 10 



31—40 5 



41—50 1 



Total 32 



Humidity among plants lower than humidity of house. 



0—10 4 



11—20 2 



21—30 1 



31—40 1 



Total 8 



For several weeks it appeared as though, contrary to all accepted 

 notions, the crowded plants were going to produce better plants and a 

 larger crop than those that had had plenty of room. As has been already 

 recorded, however, signs of deterioration gradually set in, especially 

 among the plants in the middle of the square, and by the time the 

 plants were cut marked differences were noticeable. The chief points of 

 difference are noted under their several heads. 



1. Number of ears. When the ears were counted half the crowded 

 plants possessed none at all, while all the spaced plants but three had 

 one or more, thirty-nine of them possessing from 6-8 ears apiece. In 

 toto the 64 crowded plants only produced 178 ears while the 64 spaced 

 ones had 362, more than double the number being formed when adequate 



