150 THE SOCIAL LIFE OF ANIMALS 



Chicago cockroaches could not carry over the effects 

 of training from one day to the next. 



The reason for this difference between our cock- 

 roaches and those around St. Louis and in Germany 

 is not known. It may be that at the University of 

 Chicago, despite our reputation for scholarship, the 

 local cockroaches have a low IQ, or it may be that 

 since we used animals from the bacteriological lab- 

 oratory, because of their unusual size and physical 

 vigor, we were unconsciously selecting the dumber 

 sort. Or perhaps, contrary to our plan, we set them a 

 problem which is intrinsically more difficult for the 

 cockroach mentality. In any event, it is important to 

 remember that our cockroaches forgot overnight any- 

 thing they may have learned the day before. As it 

 turns out, this was fortunate for the experiments we 

 were carrying on, because we could match up indi- 

 vidual cockroaches with the same speed of learning 

 in pairs or groups of three for later tests without fear 

 of a carryover from their previous experience. 



The maze used is shown in Figure 26. It consisted 

 of a metal platform from which three runways ex- 

 tended, each about two inches wide and a foot or so 

 long. The two side runways ended blindly, but the 

 center one led to a black bottle, which allowed the 

 cockroaches to escape from the light. This apparently 



