308 



CHEMICAL SENSES 



20 



O 



16 



I 4 



12 



10 



4 - 



Quadrant 2 



Quadrant I 



Quadrant 3 



Quadrant 4 



Site of Chemical Stimulation 



Figure 26 Data from Fig. 23: regressions of the statistic represent- 

 ing the direction vectors of steps between turns. From Kleerekoper 

 etal. (1975). 



greatly diminished discrimination of the release sites. This is evident also 

 from the behavior of the values for the direction vector. The relationship 

 between this vector and percent of distance traveled indicates that although 

 the shark's locomotor pattern centered about the release site, its radius 

 exceeded a quarter of a tank. 



A summary of the differences of all six locomotor variables in flow and 

 nonflow conditions is presented in Table 1 for quadrants 1 (upstream) and 4 

 (downstream). The table clearly shows that all the significant differences 

 occur downstream (quadrant 4), where the gradient is strongest. This leads 



