Full-grown adult as well as young rabbits were employed. The diet
consisted either of carrots or of oats; water was given ad libitum. The
rabbits were kept in metal cages in a well-lighted and well-ventilated
room. Unnecessary handling or any other procedure tending to fatigue or
to cause discomfort to the animals was very carefully avoided, since we
had found that such treatment was likely to decrease the resistance of
the rabbit to caffein. The caffein was administered by feeding by mouth
and through a stomach tube, or by the subcutaneous method. In a good
many cases it was given daily, in some at longer intervals.