been up late, let us say, or has been for a long walk, or has missed a meal; obviously his reaction-times, his record for memory, and so on, will show a difference for the worse. Or, again, the subject may confront the experiment in very various moods. At one moment he may be full of vanity, anxious to show what superior qualities he possesses; whilst at another time he will be bored. Not to labour the point further, these methods, whatever they may become in the future, are at present unable to afford any criterion whatever of the mental ability that goes with race. They are fertile in statistics; but an interpretation of these statistics that furthers our purpose is still to seek. But surely, it will be said, we can tell an instinct when we come across it, so uniform as it is, and so independent of the rest of the system. Not at all. For one thing, the idea that an instinct is apiece of mechanism, as fixed as fate, is quite out of fashion. It is now known to be highly plastic in many cases, to vary considerably in individuals, and to involve conscious processes, thought, feeling and will, at any rate of an elementary kind. Again, how are you going to isolate an instinct? Those few automatic responses to stimulation that appear shortly after birth, as, for instance, sucking, may perhaps be recognized, since parental training and experience in general are out of the question here. But what about the instinct or group of instincts answering to sex? This is latent until a stage of life when experience is already in full swing. Indeed, psychologists are still busy discussing whether man has very few instincts or whether, on the contrary, he appears to have few because he really has so many that, in practice, they keep interfering with one another all the time. In support of the latter view, it has been recently suggested by Mr. McDougall that the best test of the instincts that we have is to be found in the specific emotions. He believes that every instinctive process consists of an afferent part or message, a central part, and an efferent part or discharge. At its two ends the process is highly plastic. Message and discharge, to which thought and will correspond, are modified in their type as experience matures. The central part, on the other hand, to which emotion answers on the side of consciousness, remains for ever much the same. To fear, to wonder, to be angry, or disgusted, to be puffed up, or cast down, or to be affected with tenderness--all these feelings, argues Mr. McDougall, and various more complicated emotions arising out of their combinations with each other, are common to all men, and bespeak in them deep-seated tendencies to react on stimulation in relatively particular and definite ways. And there is much, I think, to be said in favour of this contention.