422 DR. E. J. SALISBURY ON THE 
Apart, then, from the cultivating action of worms and the attrition of the 
soil particles due to their very muscular gizzard, the change which they 
effect on the reaction tends towards a reversal of the natural reaction gradient 
in uncultivated soils. Considerable evidence has accumulated in recent 
years showing the importance of both the direct and indirect effects of 
reaction in determining the distribution of plants, and a similar relation 
would appear to exist between reaction and some animals. 
Fic. 3 
% 
0-3 
w Garbonote 
content 
W of Soil and 
Wormcasts 
(Average S) 
© 
um 
£ 
a 
WesTwca-Agrostis Polytrichum Serul Colney Heath Colney H. » x 
Vent pots Ue VIS Olego hetfon 
hardy 
Several years ago the writer drew attention to the poor soil Fauna of acid 
woodlands as compared with those in which the soil was neutral or alkaline, 
