1896 | CURRENT LITERATURE 175 
herbaceous plants (mostly Scirpus-like), rock societies, herb and shrub vege- 
tation in salty sand and gravel, tropical sand-beach woods, leafless halophyte 
woods in sand, herb and shrub vegetation in clay soil (lagoon thickets, salt 
steppes), salt deserts, and beach meadows. 
The mesophyte societies form the subject of section seven. The general 
condition is freedom from extremes. The vegetation is rich and dense, and 
there is great richriess in leaf forms. This is the common vegetation of 
temperate regions and includes the numberless new societies of weeds and 
culture plants introduced by man. The grouping of mesophyte societies is 
into grass and herb societies and societies of woody plants. Under the former 
are included arctic or alpine grass or herb carpets, meadows, pastures on 
cultivated lands; under ‘the latter, thickets, deciduous woods in temperate 
zones, and evergreen foliage woods (subtropical, antarctic, tropical rain 
woods, palm woods, bamboo woods, fern woods). 
The last section discusses the struggle between plant societies. After 
general introductory remarks concerning the nature of the struggle, the 
facts of overproduction, the easy derangement of the organic equilibrium, 
etc., the main topics discussed are the production of new soils and their 
occupation, changes in vegetation induced by slow changes in soil, changes 
in vegetation without changes in climate or soil, the weapons for the strug- 
gle, rare species, the origin of species. We have space for fuller statement 
of but two of these topics. The general characteristics of vegetation occupy- 
'Ng new soil are given as follows: The first vegetation is sparse and open; 
the number of species is small at first, then larger when the physiognomy is 
diverse, then comes an equilibrium and fewer species; annuals and biennals 
are common at first, but afterwards subordinated to perennials; the first 
Species are those whose seeds are carried by winds and birds ; light-trees 
appear before shade-trees; there isa gradual] transition to former conditions, 
and thus there may be primal, transitional and final plant societies. In refer- 
fnce to the origin of species, the author believes that plants possess an 
inate power of ada 
Others are acquired variability, depending upon descent and not 
vironment; natural selection ; crossing of species; and correlation 
Th 
plan a moment's notice. Very few references are made to American 
J ena chiefly because they have not been investigated sufficiently.— 
