76 Contributions to the Biology of Freshivater Fishes 



Summary of Results, 



Field-work was done in the area from which the samples were drawn 

 to determine how far the laboratory experiments agreed with the con- 

 ditions present. 



The distillery effluent has a very marked effect on the bed of the 

 stream. 



A very small tributary of the main stream on the banks of which 

 only one distillery is present was selected. 



Above the distillery the water was clear and fish were abundant, 

 below the distillery for about a mile no fish were found. The distillery 

 efiluent is allowed to settle a fittle but reaches the stream as a yeast- 

 coloured Uquidl The stream is coloured a short distance below outflow 

 and as the debris settles a filamentous fungus appears covering the stones 

 with a grey flocculent growth. 



The species of fungus was not determined but it covers the stones 

 for over a mile down the stream when it gradually thins out where the 

 stream becomes normal again and fish appear. When the fungus has 

 fructified it turns black and gives rise to a black shmy mud of a very 

 offensive nature and makes the stream look black. 



The distillery effluent contains a large amount of nitrogen from the 

 yeast and barley and unused up starch grains. Below the woollen mill 

 no fish were present on account of the high alkahnity which prevails 

 at times together with waste dye-stuffs. The crude sewage gives rise to 

 fungal growths very similar to that from the distilleries, but in less 

 amounts. 



