The word “memory” or “remembering” is commonly used in a number of different senses, which it is important to distinguish. More especially, there is a broad sense, in which the word applies to the power of repeating any habitual act previously learnt, and a narrow sense, in which it applies only to recollection of past events. It is in the broad sense that people speak of a dog remembering his master or his name, and that Sir Francis Darwin spoke of memory in plants. Samuel Butler used to attribute the sort of behaviour that would usually be called instinctive to memory of ancestral experience, and evidently he was using the word “memory” in its widest possible sense. Bergson, on the contrary, dismisses “habit-memory” as not true memory at all. True memory, for him, is confined to the recollection of a past occurrence, which, he maintains, cannot be a habit, since the event remembered only occurred once. The behaviourist maintains that this contention is mistaken, and that all memory consists in the retention of a habit. For him, therefore, memory is not something requiring special study, but is merged into the study of habit. Dr. Watson says: “The behaviourist never uses the term ‘memory’. He believes that it has no place in an objective psychology.” He proceeds to give instances, beginning with a white rat in a maze. On the first occasion, he says, it took this rat forty minutes to get out of the maze, but after thirty-five trials he learnt to get out in six seconds, without taking any wrong turnings. He was then kept away from the maze for six months, and on being put in it again he got out in two minutes, with six mistakes. He was just as good as he had been before at the twentieth trial. We have here a measure of the extent to which the habit of the maze had been retained. A similar experiment with a monkey showed even more retentiveness. He was put into a problem box which at first took him twenty minutes to open, but at the twentieth trial he opened it in two seconds. He was then kept away from it for six months, and on being put back in it he opened it in four seconds. With human beings, we know that many of the habits we learn are retained through long periods of disuse--skating, bicycling, swimming, golf, etc., are familiar instances. Perhaps Dr. Watson goes a trifle too far when he says: “If a poor shot or an inexpert golfer tells you that he was good five years ago but that lack of practice has made him poor, don’t believe him; he never was good!” At any rate, this is not the belief of violinists and pianists, who consider it essential to practise every day. But even if it be somewhat of an exaggeration, it is certainly true that we retain bodily habits pretty well. Some, such as swimming, seem to be more completely retained than others. The power of talking a foreign language, for example, is one which is greatly impaired by disuse. The whole matter is quantitative, and easily tested by experiment.