108 Pub. Puget Scund Biol. Sta. V^ol. 2, No. 39 



CHART 1 



Graph 1 shows the movement of herring in the gradient tank shown 

 in figures 2 and 3 of plate 19. The back and forth movement of the 

 animal is drawn to a vertical time scale with minutes divided into ten- 

 second periods. The fish started in the pure sea-water end of the tank, 

 reached the other end in about 15 seconds, and turned back, reaching the 

 point where it started at the end of 35 seconds. The dark portion of 

 the heading indicates a substance added to the sea-water and gives a 

 rough idea of the concentration which decreases from left to right. In 

 this graph, enough acid was added to the sea-water to lower the pH 

 from 8.2 to 8.1; the herring avoided the more acid water. The vertical 

 lines indicate thirds of the tank. 



Graph 2 shows the reaction of a viviparous perch in a tank the same 

 as shown in graph 1. Enough sulphuric acid was added to change the 

 pH from 8.2 to 8.1 and the perch selected the more acid water. 



Graph 3 shows the avoidance of 0.8 part per million of sulphurous 

 acid by a herring. 



Graph 4 shows a positive reaction of a perch to 60 parts per million 

 of sulphurous acid, which resulted in intoxication in 3.5 minutes. The 

 crossefs indicate intoxication after which death followed. 



Graph 5 shows a positive reaction of herring to the same concen- 

 tration of sulphurous acid. This suggests a possible danger from sul- 

 phurous acid, but the positive reaction takes place only in concentrations 

 usually higher than the undiluted Miles Process sludge; X's as in graph 4. 



Graph 6 shows the reaction of a viviparous perch to calcium nitrate. 

 It is possibly very slightly negative. The alkalinity of the water is in- 

 creased by it, as shown by the figures at the end which indicate the pH. 



Graph 7 shows the positive reaction of a herring to N/2500 normal 

 calcium nitrate; figures as in graph 6. 



