ECOLOGICAL STUDY OF BRUSH LAKE. 1 53 



of Columbus. Probably the most important factor is the presence 

 of Sphagnum, which is abundant in some parts of the Licking 

 Reservoir. But why the Sphagnum should be abundant in the 

 reservoir and entirely absent in Brush Lake is not so apparent. 

 The general character and surroundings of Brush Lake are much 

 the same as those of the " Three Sisters." 



For the present the writers will content themselves with a 

 report of the conditions as found at Brush Lake, leaving gener- 

 alizations to some future ecologist. No special work could be 

 carried on in regard to physiological adaptations. In order to do 

 such work it is necessary that one should be able to live with his 

 plants for a considerable period of time. But ecological phyto- 

 geography is still in its embryonic stage and it is perhaps better 

 for the present to continue work more along geographical lines 

 until better facilities are at hand for accurate and continuous 

 observations on physiological adaptations. Besides, our present 

 plant societies are being destroyed so rapidly that it is of primary 

 importance that an historical record should be made. This may 

 be of the utmost importance in the future. 



THE PLANT SOCIETIES. 



As stated above, the plant societies of the lake are arranged 

 in concentric zones, as is usual where there is a gradual change 

 in the environment. The zones determined are as follows : 



1. Submerged Zone. 



2. Water-lily Zone. 



3. Half-submerged Zone. 



4. Decodon Zone. 



5. Uliginous Zone. 



6. Shrub Zone. 



7. Forest Zone. 



Of these, all may be regarded as normal except the uliginous 

 zone, which to a large extent represents a recent society developed 

 on the mud flats intercalated between the Decodon and shrub 

 zones on the east and west sides of the lake. 



1. Submerged Zone. In this zone existence is almost 

 entirely under water, for rarely do any of the plants composing 

 it have even their tips extending above the surface. It is essen- 

 tially a Potamogeton-Ceratophyllum-Myriophyllum-Chara zone. 



