PLANTS OF THE MOORLAND 109 



parts are left behind and are said to be very stimu- 

 lating 1 to the grass. 



It might be objected that the above-ground 

 growths the Mushrooms, for instance are fed from 

 the soil through the food-absorbing hyphse, and that 

 if the Mushrooms are devoured by a Snail, that means 

 a final loss to the soil. But two points should be 

 noticed: that the above-ground growths contain a 

 large percentage of water, and, second, that the Snail 

 must return part of what is eaten to the soil, and that 

 when the Thrush that eats the Snail is killed, perhaps, 

 by a very severe frost in winter, and is rotted away on 

 the ground there is a bigger return still. 



The idea of the circulation of matter, already 

 alluded to in our studies, is fundamental. The grow- 

 ing green plants which have used the power of the 

 sunlight to build up out of air, water, and salts such 

 complex substances as sugar, starch, and proteins, 

 come in the course of time to an end, or it may be 

 that they only shed their leaves. The withered parts 

 are taken beneath the ground by earthworms, and 

 parts of them become food for the white threads of 

 the Mushrooms, which, having no green pigment, or 

 chlorophyll, are unable to build up organic com- 

 pounds for themselves. The activity of the white 

 threads results in the material of the above-ground 

 Mushrooms, and in substances which stimulate the 

 growth of Grass; and parts of the white threadwork 

 are always rotting away. The Mushrooms are eaten 

 by the Snail, and the Snail by the Thrush, and from 

 both there may be a return of materials to the ground, 

 to enter again into the magic circle of life. For thus 

 the world goes round. 



