388 Wisconsin Academy of Sciences, Arts, and Letters. 
is the limit of Zone 1. From this point the bottom falls away more 
or less gently to about 6 meters, the flora passing from that in¬ 
cluded in Zone 2 to that characteristic of deeper water. At about 
6 meters the slope usually becomes much steeper and the outer 
strip of vegetation hangs, as it were, to the brow of a hill. The 
plants often cease quite sharply at 8 meters, as if an invisible 
boundary were holding them in check; on one side they rise two 
or three meters high, and packed closely together; on the other 
side there is nothing but the smooth mud sloping away towards 
the bottom of the lake. 
In many places, however, the slope continues gentle to a much 
greater depth; in these cases the vegetation does not come to a 
sudden end, but thins out gradually down an imperceptible slope. 
In one such station (25) plants were found growing at a depth of 
10 meters, though small and stunted in growth. Such gently slop¬ 
ing places are found around the entire west end of the lake, op¬ 
posite Woods Bay, at Forest Glen, and thence up to Dartford Bay. 
In the west end of the lake and in parts of the east end, this gentle 
slope occurs in connection with wide sandy beaches. Figures 5 and 
6 show the difference between these two sorts of stations. 
Pig. 5. Diagram of portion of lake floor bearing attached plants. Medium slope. 
Fig 6. Diagram of portion of lake floor bearing attached plants. Gentle slope. 
