I will suppose a precursor of the Calicurgi (The Calicurgus, or Pompilus, is a Hunting Wasp, feeding her larvae on Spiders. Cf. "The Life and Love of the Insect": chapter 12.--Translator's Note.) dwelling in the prehistoric coal-forests. Her prey was some hideous Scorpion, that first-born of the Arachnida. How did the Hymenopteron master the terrible prey? Analogy tells us, by the methods of the present slayer of Tarantulae. It disarmed the adversary; it paralysed the venomous sting by a stroke administered at a point which we could determine for certain by the animal's anatomy. Unless this was the way it happened, the assailant must have perished, first stabbed and then devoured by the prey. There is no getting away from it: either the precursor of the Calicurgi, that slaughterer of Scorpions, knew her trade thoroughly, or else the continuation of her race became impossible, even as it would be impossible to keep up the race of the Tarantula-killer without the dagger-thrust that paralyses the Spider's poison-fangs. The first who, greatly daring, pinked the Scorpion of the coal-seams was already an expert fencer; the first to come to grips with the Tarantula had an unerring knowledge of her dangerous surgery. The least hesitation, the slightest speculation; and they were lost. The first teacher would also have been the last, with no disciples to take up her work and perfect it. But fossil instincts, they insist, would show us intermediary stages, first, second and third rungs; they would show us the gradual passing from the casual and very incorrect attempt to the perfect practice, the fruit of the ages; with their accidental differences, they would give us terms of comparison wherewith to trace matters from the simple to the complex. Never mind about that, my masters: if you want varied instincts in which to seek the source of the complex by means of the simple, it is not necessary to search the foliations of the coal-seams and the successive layers of the rocks, those archives of the prehistoric world; the present day affords to contemplation an inexhaustible treasury realizing perhaps everything that can emerge from the limbo of possibility. In what will soon be half a century of study, I have caught but a tiny glimpse of a very tiny corner of the realm of instinct; and the harvest gathered overwhelms me with its variety: I do not yet know two species of predatory Wasps whose methods are exactly the same.