Nor is it enough for him, when thus engaged, to take note simply of physical features--the shape of the skull, the colour of the skin, the tint and texture of the hair, and so on.

There are likewise mental characters that seem to be bound up closely with the organism and to follow the breed.

Such are the so-called instincts, the study of which should be helped out by excursions into the mind-history of animals, of children, and of the insane.

Moreover, the measuring and testing of mental functions, and, in particular, of the senses, is now-a-days carried on by means of all sorts of ingenious instruments; and some experience of their use will be all to the good, when problems of descent are being tackled.
Further, our student must submit to a thorough grounding in world-geography with its physical and human sides welded firmly together.

He must be able to pick out on the map the headquarters of all the more notable peoples, not merely as they are now, but also as they were at various outstanding moments of the past.