114 Wisconsin Academy of Sciences, Arts, and Letters. 
as it was gradually cut down. The present level of the lake is 
controlled by the government dam at Menasha. The preglacial 
channel of the Fox Eiver lies to the east of the present outlet, 
toward Clifton, but it was filled with glacial material, thus block¬ 
ing the old outlet; this compelled the lake to find the lowest avail¬ 
able col or notch which chanced to be at the present sites of Neenah 
and Menasha (see Whitbeck, 1915; Martin, 1916; Goldthwait, 1907; 
Alden, 1918). 
C. Lake Physiology 
Many agents, which may be called physiological, affect the habi¬ 
tats in Lake Winnebago. Among these, winds and waves are 
potent factors in shaping the physiography of the shores and con¬ 
sequently the character of the animal inhabitants. The great sur¬ 
face area of Lake Winnebago provides a fertile field for the action 
of winds, which disturb the surface of the lake and often descend 
to considerable depths. A severe gale from the northeast causes 
waves of great length and height and provides an undertow which 
disturbs the bottom to a depth of two meters or more. These heavy 
waves have made the peculiar rocky shores seen ,on Doemel Point, 
Asylum Point, Stony Point, and other places. Sand, gravel, and 
cobbles are constantly being carried from one point to another, 
profoundly affecting these habitats. In many places the waves and 
undertow have formed off-shore bars or shoals composed mostly of 
sand, the water being a third of a meter in depth on the bars and 
a meter or more between the bars. Gravel and cobble bars have 
also been formed off every point, in several places in water as deep 
as three meters. Plant zones are profoundly affected by wave 
action, being absent or scanty where this action is heaviest and 
most abundant where it is lightest. 
Temperature. The temperature of a shallow lake like Winne¬ 
bago is high in summer and low in winter; ice is formed in Lake 
Winnebago much earlier than in deeper lakes, which do not lose 
their heat as quickly. On account of its shallowness, there is no 
thermal stratification of the water in summer. 
Transparency. The degree of transparency of the water of 
Lake Winnebago varies with the season and with the climatic con¬ 
ditions. During July and August, 1920, the turbidity of the 
water was great and transparency was reduced to a minimum. A 
