344 MR. T. W. WOODHEAD ON THE 
of this district. Thus, in many respects, each species is not within 
the sphere of influence of the other, and they flourish aecordingly. 
Competition such as it is goes on between individuals of the 
same species. When, however, Pteris increases in density, the 
tendency is to markedly reduce the flowering activity of Holcus. 
Its tips early show signs of withering, its period of vegetative 
growth is limited, and eventually its distribution becomes 
stricted. In the late winter and early spring, however, it grows 
apace and makes great headway before the Bracken develops. 
Fig. 6. 
D 
Vertical Section of Soil in dense Scilla area: Holcus, 
Pteris, and Scilla layers. 
The chief elements in the Meso-pteridetum of the moist Coal-Measure 
Oak Woods, showing their relations to each other in the soil. 
These observations support those of Areschoug (1), Rimbach 
(81), P. E. Müller (72), and others, a very useful suminary of 
whose work has been given by Oliver (74), and more recently, 
with further interesting results, by Massart (65). 
This association or Meso-pteridetum is very characteristic of 
