SIXTH ANNUAL MEETING 23 



seilles dam. and a consequent thorough aeration of the water, 

 the dissolved oxygen in the stream a mile below the dam be- 

 ing about two and a half times that immediately above the 

 dam, and the carbon dioxide being at the same time reduced 

 by 21 per cent. In the eighty-three miles of the river between 

 Morris and Chillicothe. the dissolved oxygen of the water in- 

 creased 183 per cent, and the carbon dioxide diminished 22 

 per cent. 



A summary of the parallel changes in the biology of the 

 stream is not possible at this time. It must be said, how- 

 ever, that fishes appeared in our collections, even under mid- 

 summer conditions, in gradually increasing variety as we went 

 down the stream, from the Marseilles dam. until, at Chilli- 

 cothe. we had a fair representation of the common fish life of 

 the river. At high-water levels, and in cooler weather, fishes 

 returned, indeed, to the uppermost section of the river, al- 

 though they could be found there in only scanty numbers and 

 in comparatively small variety. Attempts were made to cor- 

 relate species and numbers of organisms obtained in the 

 river collections with diflFerent degrees of pollution or contam- 

 ination, in a way to make a classified species list available as 

 an index to such degrees. The determination of these recent 

 aquatic collections is still in progress, and the completion of 

 our report will require many weeks of additional work. 



Your committee feel that this showing of productive in- 

 vestigation is not at all to the discredit of the ecologists of the 

 Academy : but we are fully aware that most of us are still 

 working, each on his own problems in his own chosen field, 

 with no marked affiliation with the other investigators. We are 

 of the opinion that it is now particularly important that ef- 

 forts should be made to interest as many capable observers 

 and collectors as possible in a study of the remnants of the 

 prairie life of the state, now rapidly disappearing forever. 

 Preliminary to this we need as full knowledge as can now be 

 obtained of the existence and location of tracts or patches of 

 prairie turf — outside the so-called sand prairies of the state, 

 which have already been very well studied, and we appeal par- 

 ticularly to members of the Academy to advise us on this 

 point, in order that we may. without further delay, take such 

 measures as are possible for a careful study of the leading 

 types of our prairie remnants in the principal sections of the 

 state. 



Respectfullv submitted. 



S. A. FORBES. 



Chairman. 



