Carr and Watson, Orientation in the White Rat. 41 



ties, the turns would be made in a similar manner. The con- 

 ception is ingenious, and it would support our thesis, but on this 

 basis, the blind rat should have had no trouble at //. Conse- 

 quently, we are forced to admit that the phenomenon remains 

 inexplicable so far as the present experiment is concerned. 



With the exception noted above, no difference between the 

 behavior of the blind and the normal rats could be detected. 



2. The Effect of Lengthening the Maze. — After the above 

 series of tests had been completed, the rats were forced to con- 

 tinue running the shortened maze for a period of three weeks, 

 at the end of which time their reactions to it had become thor- 

 oughly automatic. The maze was then lengthened by replacing 

 the middle section, and the behavior of the animals under these 

 conditions was observed. In the previous experiment, this middle 

 section had been thoroughly explored by the animals and it 

 should now have presented a minimum of possible sensory dis- 

 turbance.^ 



The conditions are again such that they bring into func- 

 tional opposition the influences of kinaesthetic cues and any pos- 

 sible distance sense cues which might be involved in rounding 

 the corners of the alleys. If the rats turn in response to kinaes- 

 thetic cues, they should now attempt to turn in the extended 

 alleys at the positions corresponding to the length of the alleys 

 in the shortened form. In the first alley, this position is at Qf. 

 In the remaining alleys, the cul-de-sacs B, G and H now occupy 

 these crucial positions. For example, the distance S-B in the 

 extended maze equals the distance S-B^ in the shortened maze. 

 According to our theory, the rats should now run into the wall 

 at Qf and into the cul-de-sacs B, G and H. 



The results again support our contention. Marked disturb- 

 ances in conduct occurred for twelve trials (three days). After 

 this time, the disturbances occurred occasionally, though they 

 may be regarded as practically eliminated at the end of this period. 



The time for running the maze was noticeably increased in the 

 first trials, but it was gradually decreased thereafter (Table II). 



^ The blind rat whose behavior had become erratic was not used in the shortened form of the maze. 

 We utiHzed this animal, however, by allowing him each day to run several times through the lengthened 

 form of the maze. In this way, we kept the middle section constantly in use during the experiments 

 in the shortened maze. By this means, the original smell values of this middle section were retained 

 unaltered, for the males at least, since this blind rat was a male, and was kept in the same living cage 

 with all the other males used in the experiment. 



