399 



of water. In man it causes prostration, giddiness, vomiting, and 

 neuralgic pains. In fish it produces anesthesia. There is a consider- 

 able stimulation at first, quickly followed by trembling of the fins and 

 some erratic movements. The fishes turn upon their sides in two 

 minutes. They may live for hours, with their fins and gills moving 

 slightly. Five cc. per liter of water in the open battery jar killed fishes 

 after the mixture had been standing three days. Fishes are indefinite 

 or positive to the concentration used (.08-. 12 cc. per liter) (Chart 

 III, graph 23). 



Pyridine. 



It occurs in coal-tars, crude benzene, toluene, etc. In man it causes 

 paralysis of the motor centers and nerves, and movements become 

 weak and unsteady. Death follows from a failure of respiration 

 (U.S.D. ). The efifects on fishes are similar to those of many other 

 substances. Heavy respiration is usually noted early and they usually 

 die with opercles and mouth closed probably through failure of respir- 

 atory movements. Fishes are positive or indefinite in all cases studied 

 (Chart III, graph 24). 



Qtnnoline. 



It occurs in coal-tar. It is a powerful antipyretic but causes general 

 collapse. In .025 cc. per liter of water fish usually turn on their sides 

 in 10-15 minutes and continue to move their fins and gills for many 

 hours. In strong concentrations fishes are very c|uickly paralyzed and 

 there is some difficulty in determining when theV die, as movements 

 of the mouth and opercles cease long before death occurs. If the fish 

 are removed and handled roughly life may be detected by a general 

 body movement. 



A solution of it turns pink on standing and its toxicity gradually 

 falls off on exposure to air. A solution which killed fishes in 2 min- 

 utes Nov. I, killed them in i hour Nov. 13 and after several days on 

 Dec. 10. 



Fishes are usually negative in reaction to both fatal and more 

 dilute solutions, though the standard fish was positive in two cases 

 (Chart III, graph 25). 



Isoqninoline. 



Its toxic effect differs but little from quinoline. The reactions of 

 fishes are strikingly different, being usually positive instead of uni- 

 formly negative as in the case of quinoline (Chart III, graph 26). 



