CONDITIONS OF GROWTH 
13 
in a depth of spongy soil, and in the damp luxuriance of the 
hedgebank, are found growing on the almost hare sides of 
rock or wall. But in such situations they drag on hut an 
unhealthy existence, and become shrivelled in size, ungraceful 
in form, and deficient in colouring. 
The Common Polypody, the Hartstongue, and the Black 
Maidenhair Spleenwort for instance, are often found growing- 
in stony places, their rootlets getting what moisture and 
nourishment they can from the tiny seams of earth or leaf- 
mould in the interstices between the stones. But forlorn- 
looking indeed are these rock-and-wall-growing specimens 
compared with those that are found in the moist hollows of 
pollard trunks, on the dark margins of rushing streams, or in 
the depths of shady hedgebanks. 
