PERSEVERANCE REACTIONS IN PRIMATES AND RODENTS ^ 



from the midpoint of the inner boundary Hne of the exit alley, 

 hence the subject, on first entering the apparatus, is subjected 

 to none of the influences that might be contained in inequalities 

 of distance between his starting point and the four possible 

 places for exit. 



The floor of the semicircular space and that of the entrance 

 and exit alleys consist of alternate 3 mm. strips of iron and 6 mm. 

 strips of parafline. The first, third, fifth, etc., iron strips are 

 connected for continuous electrical conduction by a copper wire, 

 which is soldered to one end of each strip. The opposite ends 

 of the second, fourth, sixth, etc., iron strips are similarly con- 

 nected by a second copper wire. The paraffine strips insulate 

 adjacent iron strips from one another. The two copper wires 

 are carried to the poles of an induction coil, the position of 

 which on the table is shown in fig. 1. This coil is in turn con- 

 nected with the dry cells shown in fig. 1, and is equipped 

 with a rheostat. One of the connecting wires between the coil 

 and the dry cells is permanently attached, whilst the other is 

 unattached at its battery end, thus obviating the need of a switch. 

 I find that it is convenient and practically noiseless to close the 

 circuit between batteries and coil by merely touching the loose 

 end of the wire to the appropriate pole. It is obvious that when 

 a subject is within the enclosure or its tributary alleys he will 

 receive a shock whenever the experimenter closes the battery- 

 coil circuit. 



Figure 1 shows fii'e transfer boxes, one of which, it will be 

 seen, is drawn in sufficient detail to render separate representa- 

 tion unnecessary. These boxes are made of 1-inch Oregon pine, 

 and are all alike. They have the following inner dimensions: 

 top, 5.5 cm. X 18 cm.; bottom, 5.5 cm. x 20.5 cm.; sides, 9.2 cm. 

 X 20.5 cm. Near the inner edges of the sides are vertical grooves 

 for the reception of tin slides, which are used for opening and 

 closing the box at either of its two ends. The box top is shorter 

 than the bottom, hence it does not interfere with the vertical 

 slides as they are moved up and down within their containing 

 grooves. The slides are 5.1 cm. wide by 14.4 cm. long, and 

 each is perforated near its upper edge for the reception of a 

 lifting hook, to be described below. 



The five transfer boxes serve to block the outer apertures of 

 the entrance and exit alleys; their vertically sliding, removable 



