284 Displacement and Replacement of Associations and Species. 
the combination consists entirely, or for the most part, of indigenous species, 
€. g. — Pieridium heath; Veronica scrub. 2) Adventitious "), where the species 
are whölly, or for the greater part, exotic and’ where the influence of man has 
been indirect merely e. g. — Rubus-thicket; Digitalis herb-field. 3) Artificial, 
where definite associations are purposely made by the direct action of man, 
©. g. — Eucalyptus forest; Alopecurus pratensis-Poa trivialis meadow. Besides 
these induced associations, there are also primitive ones more or less changed 
‚ and containing probably a foreign element but still preserving the original 
stamp; such are here called “Modıfied associations”, e. g. — much of the grass- 
steppe; milled forest. A distinction must also be drawn concerning those advent- 
itious communities, or even the indigenous-induced which occur as successions 
both in modified and artificial associations, e. g. — Danthonia steppe; Phor- 
mium Swamp after draining Typha-Phormium swamp, in fact there are here, 
‚as in all classification, various anomalies. An account of the origin of the 
many non-primitive associations is beyond the scope of this work, here all 
that can be given are a few examples of the more important and distinct or 
of those that may teach some special lesson. 
2. Displacement and Replacement. 
DR, 
earl 
