214 E. C. MACDOWELL AND E. M. VICARI 



normal rats in a litter were raised in cages directly above the 

 cages of their respective brothers and sisters that were being 

 alcoholized, in order to equalize the possible influence of the 

 immediate surroundings. Before maturity the rats were sepa- 

 rated into pairs; from each litter an equal number of alcoholic 

 and normal pairs were mated. No alcohol was given to the rats 

 in the subsequent generations. The largest rats among the 

 offspring were chosen as parents of the next generation, with no 

 knowledge of their training records. As many rats as possible 

 from these matings of the progeny of alcoholized rats were to 

 have been raised, but here again the experiment was unavoidably 

 much reduced. 



c. The alcohol tanks 



Tanks of galvanized iron, 30 by 16 by 12 inches, with tight- 

 fitting covers, held the alcohol fumes and the rats during treat- 

 ment. Inside were false bottoms of wire netting which held the 

 rats above the alcohol filling the bottoms of the tanks. The 

 covers were made with glass windows so the condition of the 

 animals could be observed. A small hole in each end, at the 

 level of the wire bottom, w^as made, on the supposition that the 

 carbon dioxide might thereby tend to escape. In an earlier 

 series of experiments the controls were daily placed in tanks of 

 the same description without alcohol, as long as the test rats 

 were in their tanks. Merely the confinement in the hmited air 

 space caused none of the symptoms observed in the rats from the 

 alcohol tanks. The alcohohzed rats would frequently remain 

 unconscious for hours after they were returned to their cages; 

 the controls upon leaving the control tanks would show no modi- 

 fication of their normal behavior. It can safely be concluded 

 that the apparent intoxication was due to the alcohol fumes, 

 and not to the confinement in tightly closed tanks. 



d. Training; apparatus and methods 



The apparatus used in training these rats was constructed 

 after the plan of Watson ('14), namely, a circular maze con- 



