132 American Fisheries Society. 



of the minute crustaceans on which the baby bass feed. It 

 is also deficient in all the elements that, under the action of 

 bacteria, change the dying aquatic plants into humus. 



Of calcium it contains less than one part per million. At 

 some of the other Bureau's stations the parts per million 

 are: White Sulphur, W. Va., 14; Erwin, Tenn., 17; Neosho, 

 Mo., 37; Wytheville, Va., 50; Northville, Mich., 60; and 

 Bozeman, Mont., 65. A comparison as to many of the other 

 elements would show a similar disparity. In free carbon 

 dioxide Cold Spring water is rich having 60 parts per million. 



The effect of a difference in amount of mineral elements 

 is clearly shown by a comparison of the higher aquatics 

 that thrive at the stations mentioned with those that grow 

 at Cold Spring station. In the ponds at these stations are 

 found Chara, Water Cress, Potomogetons, etc. In our 

 ponds grow water grasses, sedges, rushes and Starwort. 

 These are the native species. The Milfoils and Pennywort, 

 introduced species, also thrive. 



On our fish the effect of the deficiency in minerals in 

 solution and the presence of considerable free carbon 

 dioxide is shown in the high mortality of adults, often one- 

 fourth the total number, and in the number and thrift in 

 schools from domesticated stock when compared with the 

 greater numbers and more rapid growth of schools from 

 wild bass newly introduced from South Georgia waters. 



A number of experiments have been made with the 

 purpose of improving the quality of the water and of en- 

 riching the bottom soil of ponds. One year a carload of 

 stable manure was broadcast over the drained ponds and 

 worked into the soil. It failed to decompose into humus pro- 

 perly and the results were negative. 



The next year a carload of limestone, crushed to pass 

 through a screen of 100 mesh per inch, was applied to the 

 pond bottoms. No benefit could be claimed. 



This year a filter was made in a single pond. It con- 

 tained, above the gravel and sand, a barrel of newly slaked 

 burned lime. Water was forced up through it from a three- 

 fourths inch pipe under a half pound pressure. Installed 

 and put into operation last September much of the lime had 

 dissolved out by the time fish began spawning. Though 

 many eggs were spawned, no fry or fingerlings could be 

 found for collections, so about the first of May the filter 

 was disconnected. After that the pond gave good results; 

 perhaps as good or even better than any other on the place. 

 The results were not conclusive. 



The problem of providing a better fish medium was 

 undertaken in another way, beginning last summer. Ponds 



