The homing of the carrier pigeon is a good instance of activity directed in part by an inner adjustment, since, when released at a distance from home, he is evidently "set" to get back home, and often persists and reaches home after a very long flight. Or, take the parallel case of the terns, birds which nest on a little island not far from Key West. Of ten birds taken from their nests and transported on shipboard out into the middle of the Gulf of Mexico and released 500 miles from home, eight reappeared at their nests after intervals varying from four to eight days. How they found their way over the open sea remains a mystery, but one thing is clear: they persisted in a certain line of activity until a certain end-result was reached, on which this line of activity ceased. One characteristic of tendencies that has not previously been mentioned comes out in this example. When a tendency has been aroused, the animal (or man) is tense and {79} restless till the goal has been reached, and then quiets down. The animal may or may not be clearly conscious of the goal, but he is restless till the goal has been attained, and his restlessness then ceases. In terms of behavior, what we see is a series of actions which continues till a certain result has been reached and then gives way to rest. Introspectively, what we feel (apart from any clear mental picture of the goal) is a restlessness and tenseness during a series of acts, giving way to relief and satisfaction when a certain result has been reached. A hungry or thirsty animal is restless; he _seeks_ food or drink, which means that he is making a series of preparatory reactions, which continues till food or drink has been found, and terminates in the end-reaction of eating or drinking. What the Preparatory Reactions Accomplish