A model of chronic alcohol intake under free-choice conditions. 
The preference of 42 Wistar male rats for alcoholic or non-alcoholic solutions of glucose was studied.  Preference for the left or right position of drinking tubes did not appreciably influence the choice between the unequal solutions.  Within the same strain of rats the majority of the animals had a high and a minority a low level of consumption of the glucose-alcohol solution.  These groups were found only under conditions of systematic experimentation and the properties of each group became more marked in the course of these experiments.