PLATE 21 
Agaricus tabulans: 
A. —Effect of a ring on Kubanka wheat. The wheat at the left shows normal 
production on the plot; at right, the straw is weak, the heads are poorly filled and 
prematurely ripened. The yield of dry matter at the left was 500 gm. per square 
meter; at the right, 400 gm. Even a greater difference was shown in the yield of 
grain, that in the ring being 63 gm. and that outside being 137 gm. per square meter. 
In this case the yield in dry matter inside Was only 80 per cent of that outside and 
the yield of grain only 46 per cent. Akron, Colo., August 10, 1915. 
B. —The stubble showing the distribution of the ring of A. tabularis . The wheat 
ripened off early in the ring, and the straw turned dark. The farther end of the trench 
shown in figure 2 ended at about the middle of the foreground of this picture. Akron, 
Colo., August 16, 1915. 
