146 The Ohio Journal of Science [Vol. XXI, No. 5, 



B. Ecology of the Pond as a Whole. 



Mirror lake, so artificial in origin and history could not 

 well be compared directly with natural ponds or lakes. The 

 larger pond was hopelessly artificial for the most part (and is 

 more so now) lacking in many environmental factors that 

 would make favorable habitats for many types of animals. The 

 scarcity of animal forms found there amply illustrates that. 

 The smaller pond soon outgrew its artificial aspect. The shore- 

 line was less artificially maintained and a good development of 

 plant life of some kinds allowed. 



The formations or habitats of typical ponds Shelf ord ('13), 

 enumerates as: (1) pelagic formation (better called limnetic), 

 (2) pioneer formation, (terrigenous bottom), (3) submerged 

 association, and (4) association of emergent vegetation. 



Number 1 was present in Mirror Lake, though little repre- 

 sented in the small pond. As terrigenous bottom means a bare 

 bottom, which eventually gives way to rooted vegetation, num- 

 ber 2 was, strictly speaking, not present. Except in the shore- 

 ward areas the bottom was soft, dark mud, with humus added 

 to it. Number three was developed in the small pond (com- 

 prising algas only) but practically absent in the large. Unless 

 one consider the slightly submerged shore grasses in parts, 

 number four was also absent. 



From the standpoint of the development of a typical pond 

 fauna the greatest deficiency was this of the emergent vegeta- 

 tion, which implies shoreward areas of cat tails, rushes, arrow 

 heads, etc., and water lilies on the open water side. Ponds 

 richest in life have a good development of such association 

 together with a submerged association. 



The large pond (with the exception of station 9 and vicinity) 

 lacks characteristic floral and faunal features of ponds which, 

 by Shelford's ('13) definition "are usually very largely cap- 

 tured by vegetation which is very much like that in the bays 

 of lakes." Neither is it a lake. It is just an artificial body of 

 water, called pond rather than lake, because of its small size, 

 which, cannot be made to conform closely to anything in nature. 



C. Ecological Habitats and Grouping of Stations 



Into Habitats. 



Division into ecological habitats is especially difficult where 

 the body of water is so generally of a uniform nature as is the 

 larger part of Mirror Lake. 



