Oct. 29,1917 
Fungus Fairy Rings 
235 
area consists of only a narrow zone near the edge of the ring, while in 
A. tabidans the zone extends far back toward the center of the ring. 
From our results it seems likely that the greater amount of stimulation 
noted on the native sod and cultivated crop is due to the reduction of 
the nitrogenous organic matter to available nitrates and salts of ammonia, 
and to the subsequent decay of the fungus filaments which produce the 
same compounds. A stimulation of vegetation exactly similar to that 
in the fairy rings was produced artificially at Akron, Colo., by placing 
ammonium nitrate in shallow holes in the soil and by scattering it over 
the surface of the soil during the rainy period. 
The investigations thus far conducted indicate that the stimulation 
of the grasses and other vegetation is due principally to the presence in 
the soil of nitrates and salts of ammonia which are derived from (1) the 
reduction of the organic matter of the soil; (2) the decay of the fungus 
fruits; and (3) the decay of the mycelium. 
Table XXIV. —Effect of fairy rings on the chlorophyll content of plants , Akron , Colo., 
1915a 
RINGS OP CALVATIA CYATHIFORMIS, JUNE 2 8 
Plant. 
Percentage of alcoholic extracts of 
crude chlorophyll. 
Outside. 
In stimu¬ 
lated zone. 
Inside. 
Bouteloua gracilis . 
Per cent. 
IOO 
100 
IOO 
IOO 
Per cent. 
340 
280 
I7S 
no 
Per cent. 
12? 
120 
127 
105 
Plantago purshii . 
Bouteloua gracilis . 
Plantago purshii . 
Mean. 
IOO 
226 
119 
RINGS OF AGARICUS TABULARIS, JUNE 18 
Gutierrezia sarothrae . 
IOO 
no 
90 
200 
Artemisia frigida . 
100 
200 
Malvastrum coccineum . 
IOO 
225 
200 
300 
90 
! I 35 
1 135 
[ 255 
Festuca octoflora ...:.. 
IOO 
Hedeoma nana .. 
IOO 
200 
Plantago Purshii . 
IOO 
265 
260 i 
Bulb His dactyloides . 
IOO 
Mean. 
IOO 
209 
172 
a The chlorophyll was extracted from equal areas of leaf lamina by cold 90 per cent methyl alcohol. The 
extract was made in the dark. Colorimetric determination was made on the crude extract, the values 
outside being taken as 100. 
CHLOROPHYLL CONTENT 
One of the most characteristic features of fairy rings is the deep-green 
color of the vegetation in the stimulated zones. This effect was noted by 
many investigators, but no quantitative determinations of chlorophyll 
content have been made. The writers have determined by colorimetric 
