134 COMMUNITIES OF SMALL LAKES 
I. THE INFLUENCE OF SIZE AND DEPTH 
Size and depth have a marked influence on the rate of succession. 
If the lake is large, like Lake Michigan, its waves beat upon the shores 
with such force as to prevent the development of vegetation or the 
establishment of any of the formations just discussed. Smaller lakes 
have proportionally less efficient wave-action, and situations which would 
not be protected to any marked degree in a lake like Lake Michigan are 
relatively free from effective wave-action. The formations succeed one 
another rapidly where wave-action is slight. The various parts of the 
shore of a small kettle-hole with a regular shore-line would pass through all 
these stages at nearly the same rate. Depth is an important factor also 
because the various formations cannot succeed over the deep water until 
the deeper parts are filled (or drained), which often requires long periods. 
The rate of succession in lakes is then directly proportional to their size 
and depth. The small lakes pass through all the stages more quickly 
than the larger lakes. Those considered here have for the most part, at 
present, become dominated by the late stages. The lakes of the inland 
type which are large enough to maintain all the formations discussed are 
among the most complex of all our habitats. 
2. INFLUENCE OF MATERIAL AND MODE OF ORIGIN 
At the very beginning the kind of material in which a lake is situated 
is important but as time goes on it becomes less and less important. If 
the lake is in clay, at the outset there are no sandy areas, but the action 
of the waves soon removes the finer material and leaves sand (the finer 
materials being deposited on the bottom of the lake). Young lakes in 
rock are probably very different from those in clay, but even here sandy 
shores are soon formed and occupied by the same animals as sandy 
shores of different origin. 
The distinction between lakes and ponds is a purely artificial one. 
The ponds have the same communities at the outset as the lakes, but 
the changes proceed so rapidly that very young ponds are rare. All 
lakes and ponds tend to become ecologically similar, regardless of mode 
of origin and kind of material. 
LIST Lt 
The following Entomostraca have been taken from Wolf Lake: * indicates the 
species is found in Fox Lake; { in Butler’s Lake; { in the series of ponds at the 
head of Lake Michigan: Copepods: {*} Cyclops serrulatus Fischer; *t} C. albidus 
Jurine; {C. viridis brevispinosus Herrick. Cladocerans: Acroperus harpae Baird; 
t Scapholeberis mucronata Muel.; }{ Pleuroxus denticulatus Birge; Diaphanosoma 
brachyurum Liev.; t Chydorus sphaericus Muel.; Polyphemus pediculus Linn; M acrothrix 
rosea Jurine; t Ceriodaphnia reticulata Jurine; { Simocephalus serrulatus Koch; Bosmina 
obtusirostris Sars. Ostracods: Potamocypris smaragdina Vav. 
