164 OHIO STATE ACADEMY OF SCIENCE. 
to the lake shore, in a comparatively short time the societies 
become disturbed and may make sudden advances without defin- 
itely occupying the intervening ground. 
The final result of the filling of the lake and the progression 
of the zonal societies will be a moist mesophytic forest. Near 
Brush Lake there are many small swamps and ponds, in various 
stages of destruction, which show quite strikingly what the 
actual history with any given set of conditions will be. If the 
filling is slow and uniform, the final stage before the hydrophytic 
forest is a swamp, shrub society. In these swamps the same 
shrubs mentioned above as occurring in the shrub zone of Brush 
Lake are the predominant vegetation. Cephalanthus, various 
willows, dogwoods, and swamp roses take possession and these 
are followed by the silver maple, white elm, white and red ash, 
black and peach-leaf willow, and other trees. 
There is an interesting extinct or nearly extinct pond about 
three-fourths of a mile north of Brush Lake on rather high 
ground in a small, unpastured forest. A ploughed field extends 
near one side which has evidently been responsible for some rapid 
filling in recent years. ‘The fringe of hydrophytic shrubs is still 
near the margin and just outside of this isa young and very 
thick zone of white ash. ‘The whole centre inside of the shrub 
zone is an open, flat, nearly circular area with a small depression 
in the centre about ten feet across. During dry seasons the water 
disappears entirely and the area is covered with rank moisture- 
loving weeds, while in a wet season it is covered with water sev- 
eral feet deep. 
In the fall of 1902, Nymphaea advena Sol. was present in 
the small depression in the centre, although the leaves were 
mostly dry. No pond lilies were evident outside of this depres- 
sion, although the area was carefully searched. Along with the 
Nymphaea and around it was an abundance of Polygonum 
punctatum El]l., and surrounding this was a dense growth of 
Polygonum hydropiperoides Mx. The last mentioned plant 
extended outward to the shrub zone. But at some distance from 
the centre the Polygonum was intersperced with very tall plants 
of Erechtites hieracifolia (L.) Raf. and other moist ground 
weeds as— 
