‘Now that you have collected such a mass of details, you ought to follow up analysis with synthesis and promulgate a comprehensive theory of the origin of instincts.’ There’s a rash proposal for you! Because I have turned over a few grains of sand on the seashore, am I qualified to talk about the ocean depths? Life has its unfathomable secrets. Human knowledge will be struck off the world’s records before we know all that is to be said about a Gnat. Equally obscure is the question of nest-building. By a nest we understand any residence constructed purposely to receive the eggs and to protect the development of the young. The Bees and Wasps excel in the art. They know how to make cabins out of cotton-stuffs, wax, leaves or resin; they build turrets of clay and domes of masonry; they mould earthenware urns. The Spiders vie with them. Remember the flying-machines, the rose-patterned paraboloids of certain Epeiræ; the globular bag of the Lycosa; the Labyrinth Spider’s cloisters with their Gothic arches; the Clotho Spider’s tent and lentiform pockets. [59] The Locust makes pits surmounted by a frothy chimney; the Mantis whips her glair into a frothy mass. [60] The Fly and the Butterfly, on the other hand, know nothing of these fond attentions: they limit themselves to laying their eggs at spots where the young can find board and lodging for themselves. [61] The Beetle also is generally extremely ignorant of the finer points of nest-building. By a very singular exception, the Dung-beetles, alone among the immense host of wearers of armoured wing-cases, have a special art of rearing, a system of upbringing which can bear comparison with that of the most gifted insects. How did they come by this industry? Venturesome minds, deluded by the greatly daring theorists, tell us that the science of the future, rich in evidence drawn from the mysteries of fibre and cell, will draw up an affiliation-table in which the animal kingdom will be classified so that the place occupied by a creature shall inform us of its instincts, without any need of preliminary observation. We shall determine the aptitudes by means of learned formulæ, even as numbers are determined by their logarithms. It is most impressive; but beware: we are dealing with Dung-beetles; let us consult them before we draw up the logarithmic table of instincts. The Onthophagus is related to the Copris, the Scarab and the Sisyphus, all of whom are versed in the art of making shapely pellets. Let us try to tell beforehand, according to the place which she occupies in the insect-table, going merely by the formula, what she is able to do in the way of nest-building.