Indeed, the purely temporary condition of body and mind is apt to influence the results.

A man has 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.