228 VICTOR E. SHELFORD AND W. C. ALLEE 



One observer took charge of the control, the other of the 

 experiment. At a time agreed upon, the fishes were emptied into 

 the tank near the center and were watched continuously from 

 twenty to ninety minutes. At first they nearly always moved 

 back and forth exploring the tank, and their movements were 

 recorded on the trial balance paper, in the form of a tracing 

 similar to the graphs on pp. 233, 237, 239 and 240, but with time 

 written in, instead of represented by a scale. Full notes on the 

 reflexes, risings to the surface, et cetera, were recorded on the 

 left half of the sheet. From these records, particularly from 

 the graphs, the total and fractional time spent in each end, the 

 number of turnings in the gradient and in the corresponding 

 position in the control were determined. These are shown in 

 the tables to follow. Some of the graphs were transcribed and 

 are shown (charts 1 to 4) with the actual vertical scale correctly 

 represented. 



At the end of the first period of experimentation, the fishes 

 were often removed to the small dishes while the observers 

 changed places. The control fishes were then placed in the 

 gradient tank and vice versa. Thus the same fishes were ob- 

 served by the same person in both the experimental and control 

 conditions for the same length of time. At the outset we under- 

 took the study of the reactions of fishes to boiled water, trying 

 various experiments of varying lengths and employing all the 

 species which were available. In this way we became famihar 

 with specific peculiarities and acquired skill in observing and 

 recording results. Some long experiments were performed with 

 larger numbers of fishes and their positions were read and re- 

 corded at five or ten minute intervals. The results are expressed 

 in percentages for the three major divisions of the tanks. 



In general our index of the effect of treated water upon the 

 fishes was its effect upon the rate and vigor of respiratory move- 

 ments, movements of the mouth, rising to the surface, et cetera. 

 These aspects of reactions were observed in detail in three series 

 of experiments in which fishes were put into glass boxes (Reuss 

 '10) 13 cm. by 13 cm. by 3 cm. Two individuals were used in 



