Chart III. 



Graph 21 shows the reaction of a minnow (Notropis) to approximately 0.25 

 gram of ammonium ferrocyanide per liter. The fish was active and swam back and 

 forth turning back from the pure water repeatedly. 



Graph 22 shows a slight preference on the part of an orange-spotted sunfish for 

 water containing ethylamine. 



Graph 23 shows the indifference of two orange-spotted sunfishes to about one- 

 tenth cc. of aniline per liter. 



Graph 24 shows the marked activity of two individuals of Notropis in a pyridine 

 gradient and their repeated avoidance of the pure water throughout the experiment. 



Graph 25 shows the marked negative reaction of the minnow (Pimephales) and 

 long-eared sunfish to 0.16 cc. of quinoline per liter. 



Graph 26 shows a marked negative reaction of a minnow (Notropis) to a weak 

 solution of isoquinoline. In the case of both quinoline and isoquinoline the fishes 

 were active and turned back from the polluted water; the rule for the former, and 

 the exception for the latter. 



Graph 27 shows the negative reaction of a minnow (Pimephales) to water con- 

 taining 8 cc. per liter of hydrogen sulphide. The fish became intoxicated at the 

 end of five minutes as indicated by the X in the graph. 



Graph 28 shows the positive reaction of a full-grown rock bass to two cc. per 

 liter of hydrogen sulphide. The pure water was encountered repeatedly and re- 

 peatedly avoided. 



Graph 29 shows the reaction of two orange-spotted sunfishes to approximately 

 500 cc. of sulphur dioxide per liter. The fishes spent the greater part of the time 

 in the central part of the tank. 



Graph 30 shows the positive reaction of two orange-spotted sunfishes to 5 cc. of 

 sulphur dioxide per liter. 



Graph 31 shows the positive reaction of a long-eared sunfish to water containing 

 less than 1 cc. per liter of carbon disulphide. 



Graph 32 shows the reaction of a minnow (Pimephales) under the same con- 

 ditions as graph 31. The fish was positive during the first seven minutes and nega- 

 tive during the last three. 



Graph 33 shows the positive reaction of a rock bass to a fatal concentration of 

 thiophene. 



Graph 34 shows an equally positive reaction of a long-eared sunfish. 



