458 



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



rock. Here and there a small bunch of willow shoots had 

 obtained a foothold. The crevices and narrow ledges awash 

 with the water were covered with algae. Beyond the area of 

 muck the amount of material on the bottom was at most three 

 inches deep. In some places it was not more than an inch deep 

 or barely that. This material consisted of dust from the road 

 and of a considerable amount of decayed organic substance, 

 chiefly algal. 



-»• — ^r«»^.^«Miass>*~~«- 



Part of the Fifteen Year Pond. 



The temperature of the water was 29° C. The water was 

 kept more or less constantly stirred up by cows which frequently 

 stood in one end of the pond. As a result it was so turbid that 

 the transparency disk disappeared at six inches. The turbidity 

 would have been great even had the cattle not been present by 

 reason of the great abundance of the plankton alg£e. These 

 colored the water green. The cattle also made the water so 

 foul as to give it a disagreeable odor. This was the only one of 

 the ponds in such a condition. 



The character of the pond was such that it did not seem 

 necessary to divide it into stations. All the forms have been 

 placed in a single table. Table 19, page 459. To the right, 

 opposite each species there is indicated in a word, their relative 

 abundance. 



