466 The Ohio Journal of Science [Vol. XIX, No. 8, 



Chara. This is excluding from consideration the Chara in the 

 year old pond since it became established in a pool antidating 

 the present pond. Even for the Chara in the five year pond the 

 substratum was artificially provided through the action of a 

 pump. It should be noted in this connection that vegetation 

 had already gained a footing about the five year pond, on the 

 portion of the quarry bed not covered with water. It is there- 

 fore probable that the pond would have been able to support 

 emergent vegetation if the water had not been so deep. As it is 

 we find emergent vegetation, lilies and reeds, first appearing in 

 the ten year pond. The irregularities of the situation are 

 apparent, however, in the fact that the fifteen year pond had 

 no rooted vegetation. This should be attributed to the cattle 

 or to some other cause not connected with the substratum since 

 parts of this pond offer a better foothold for vegetation than the 

 ten year pond. 



In considering the physical changes which have occurred it 

 should be kept in mind that an important factor is the relative 

 situation of the ponds with regard to sources of extraneous 

 material. Ponds which are entirely surrounded by the bare 

 bed of a quarry are not nearly so likely to be filled nor to undergo 

 alterations along their shores as are those more closely sur- 

 rounded by fields or trees. The ten year pond, for example, is in 

 most physical features no farther advanced than the one a year 

 old. The three younger ponds are so situated that by the time 

 they attain the present age of the two older ones they will not 

 have reached the present physical condition of the older ponds. 

 The evidence from this series, then, is that the physical trans- 

 formation which occurs in a rock bottom pond is not in propor- 

 tion to age, at least during the first thirty years. However, this 

 change, whatever its rate, causes such a pond to approach the 

 condition of one established on a bottom of earth. 



The Fauna. 



The distribution of the various species through the five 

 ponds of this series is summarized in Table 24, page 471. One of 

 the interesting features brought out by the summary is the great 

 number of species which are found in only one pond. Out of a 

 total of 112 species for all ponds 65 species were present in but 

 one pond, twenty-eight were in two, nine species were in three 

 of them, four were present in four ponds and five species, also, 

 were found in all of the ponds. 



