These experiments were originally undertaken f o r the purpose of studying the effect of alcohol on spontaneous activity. This approach was chosen for two reasons: first, from the biological point of view, spontaneous activity is one of the simplest, yet one of the most important, aspects of the behavior of organisms; and, second, it is amenable to quantitative measurement and control. I n the course of the investigation the original experiments were extended to include also the study of the effect of alcohol on two other aspects of behavior, hunger and thirst, both of which may be quantitatively controlled and measured in terms of daily amount of food and water intake. Observations were made also on habituation and intoxication effects.
The alcohol was given to rats in drinking water continuously over long periods of time (three to seven months), so that chronic rather than acute effects of alcohol were produced. By this method of administration all of the water that the animals drank contained a definite amount of alcohol (8 to 16 per cent per volume of all drinking water). The animals were started on the alcohol solution when at the age of twentyfive to thirty days. If the alcohol is given to them later, after they have become accustomed to drinking ordinary water, they are apt to refuse it, just as they often refuse water once 397