206 THE FORMATION 
(6) Each pioneer produces about itself a tiny area of ecesis and 
stabilization for its own offspring, for the disseminules of its 
fellows, or of invaders. 
(7) Species propagating by offshoots, or producing relatively im- 
mobile disseminules in small number, usually show effective 
ecesis, as the offspring appear within the area of the reaction 
; of the parent forms. 
V. Stabilization. 
(1) Stabilization is the universal tendency of vegetation. 
(2) The ultimate stage of a succession is determined by the domi- 
nant vegetation of the region. Lichen formations are often 
ultimate in polar and niveal zones; grassland is the final vege- 
tation for plains and alpine stretches, and for much prairie, 
while forest is the last stage for mesophytic midlands and 
lowlands, as well as for subalpine regions. 
(3) Grassland or forest is the usual terminus of a succession; they 
predominate in lands physiographically mature. 
(4) The limit of a succession is determined in large part by the pro- 
gressive increase in occupation, which makes the entrance of 
invaders more and more difficult. 
(5) Stabilization proceeds radiately from the pioneer plants or 
masscs. The movement of offshoots is away from the parent 
mass, and the chances of ecesis are greatest near its edges, in 
a narrow area in which the reaction is still felt, and the 
occupation is not exclusive. 
VI. General laws. 
(1) The stages, or formations, of a succession are distinguished as 
initial (prodophytia), intermediate (ptenophytia), and ulti- 
mate (aiphytia). . 
(2) Initial formations are open, ultimate formations are closed. 
(3) The number of species is small in the initial stages; it attains a 
maximum in intermediate stages; and again decreases in the 
ultimate formation, on account of the dominance of a few 
species. 
(4) The normal sequence of vegetation forms in succession is: (1) 
‘algae, fungi, mosses; (2) annuals and biennials; (3) peren- 
nial herbs; (4) bushes and shrubs; (5) trees. 
(5) The number of species and of individuals in each stage increases 
a constantly up to a maximum, after which it gradually de- 
creases before the forms of the next stage. The interval 
between two maxima is occupied by a mixed formation. 
