Ome day a cold-blooded Izaak Walton will write a treatise on the compleat art of man-hunting. The tracking by society of the men who prey on man is already something of a sport and something of an art — in fiction. In real life it is a crusade, a science, a profession; there is no sporting ethics in it and the police prefer the shortest way to the kill whether it is good sport art or none of these pleasant things. But the quarry has grown clever with science and tech nique. Science plays no favorites and is at the disposal of any one who masters it. Poison serves the criminal as well as the physician. The oxy-acetylene torch will burn through steel as obligingly for the bank burglar as for the steel worker. The Great War, like all other wars, taught criminals new ways of killing. So that the whole fraternity of the under world, from the petty thief who has learned enough to wear gloves when he does his looting to the murderer who uses only vegetable poisons which dissolve and leave no trace in the stomach, all these have taken on new tricks and are adding to them every day. And the hunter has had to keep up with the quarry. The result is that so infinitely complex, delicate and manifold have become the means of weapons of crime as well as those of the hunting down of criminals with radio and X-ray, dicta phone, micro-photography, chemical reagents, psychoanalysis, organization technique, card cataloguing, international police conferences and ten thousand other devices, that the modern detective has come to exercise something of the care of the artist in _choosing weapon and trail in his hunt. But it is still primarily a hunt and each race has its own tracker's tricks. It is interesting to observe, in addition to the fascination of the tricks themselves, how even in hunting down men each race reveals its racial traits.