442 Wisconsin Academy of > Sciences, Arts, and Letters. 
filiformus were the first of the species now present to gain a 
foothold. These species occupy the wetter portions of the 
marsh. Gar ex stricta is evidently a more recent arrival and 
altho of general distribution in the marsh yet reaches its 
greatest development between the wetter portions and the bor¬ 
der zone. The range of Carex stricta is N S E, while that of 
Carex aquatilis is fsT E W. This indicates that Carex aquatilis 
is more northern in its climatic requirements. 
The conditions of competition in such a dense population 
already so fully occupying the space affords a most interesting 
field for the study of development. Practically every inch of 
the ground is occupied and hence the question of seed dispersal 
is of little importance in the spread of species. The struggle 
is chiefly between species very similar in structure and adapta¬ 
tion. This struggle is severe beneath the ground for the rhi¬ 
zome development admits of steady persistent spread and gives 
rather permanent possession even after the most favorable con¬ 
ditions have ceased to exist. Yet it is noticeable that there is a 
definite grouping of species with definite areas of best develop¬ 
ment and marked zones of contact. Sligth differences in mois¬ 
ture content, in soil composition, and slight elevations or depres¬ 
sions are associated with change of species. In a habitat with 
such uniform conditions as is here found and with so many 
species of similar structure 1 , slight differences in environment 
are correlated with the individual peculiarities of the various 
species most strikingly. 
Influence of Water Level 
It is universally recognized that the amount of water in a 
soil and the level at which the ground water stands are im¬ 
portant direct factors in determining the character of the plant 
life which is present. 
A series of experiments was carried out to test the influence 
of this one factor and to determine whether there is a cor el- 
lation between depth of the water table and the root and shoot 
development. Seeds of the species that are dominant in the 
marsh meadow above described were not available when these 
