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CHEMICAL SENSES 



compartment through a subsurface orifice and flow-control valve, traverses 

 the compartment and the central open area, and leaves through a standing 

 pipe in the center of the monitor tank. The rate of flow can be regulated so 

 that the same or different flow rates can be established in the compartment. 

 The monitor is surrounded by a light trap and is located in a dimly lighted 

 laboratory room. Diffused overhead lighting is available for some experi- 

 ments. Chemical or control solutions can be introduced into one or more 

 compartments by means of solenoid pumps, the stroke paths of which can 

 be electronically controlled as to length and frequency. Sound or light 

 sources can be added, singly or in combination with other stimulus 

 modalities. 



The second system (monitor II) is composed of a tank, 5.0 m X 5.0 m X 

 0.6 m (Figures 14, 15), in the floor of which is embedded a square matrix of 

 1936 photocells on 10-cm centers, photosensitive faces upward. A con- 

 tinuous field of collimated light, suspended over the tank activates the 

 photocell matrix, which is interfaced with a digital minicomputer, a tele- 

 typewriter, a magnetic tape unit, and a plotter. The position of a photocell 

 shaded by the light interception of a passing fish and the time of this event 

 are computed and recorded, and the information is stored on a computer 

 disk pack. These raw data and their sequence form the basis for computation 

 of the position of the fish in the tank, its velocity, the magnitudes of turns, 

 the lengths and orientation of the steps, the distances covered, and the 

 frequency distributions of all these values over time. 



Figure 14 Shark monitor tank II; see Fig. 15 for explanation. From Kleerekoper (1969). 



