At 8 a. m. at Fabre's place in Serignan, one saw the cocoon of a lesser-peacock moth open; a female emerged and was immediately imprisoned in a wire cage. At noon a male arrived, the first that Fabre, who had lived there all his life, had ever seen. The wind was blowing from the north. The male came from the north, that is to say, against the scent. At two o'clock ten had arrived. Having come as far as the house without hesitation, they were troubled, got the wrong window, wandered from room to room, never went directly toward the female. One would say that at this point they should have used another sense, perhaps sight, despite their being crepuscular creatures, or that the cage bothered them. Perhaps also it is the custom for the female to come and play before them? It is, in any case, evident that sense of smell plays an important rôle; the mystery would not be less great if one supposed the bringing into play of a special sense, that of sexual orientation. Fabre has obtained equal success with the female of a very rare butterfly, the oak bombyx, or banded minime: in one morning sixty males arrived, turning about the prisoner. One has observed analogous if not identical things in certain serpents, in mammifera: everyone has seen dogs in the country, drawn by a female in heat, coming from a considerable distance, nearly a league, without one's being able to say how their organism had got the news. Explanations are vain in these matters. They divert the curiosity without satisfying the reason. What one sees clearly is a necessity: the act must be accomplished, to this end, all obstacles, whatever they are, will be overcome. Neither distance, nor the difficulty of the voyage, nor the danger of the approach can drive back the instinct. In man, who has sometimes the power to escape the sexual commandments, disobedience may have happy results. Chastity, as a transmuter, may change unused sexual energy into intellectual or social energy; in animals this transmutation of physical values is impossible. The compass needle remains in one immutable position, obedience is unescapable. That is why there is so deep a rumble in nature when the spring orders are posted. Vegetable flowers are not the only ones to open: sexes of flesh also flower. Birds, fish take on new and more vivid colours. There are songs, plays, pilgrimages. Salmon who live quietly at the river-mouths, must gather, depart, climb the streams, pass weirs, scrabble against rocks which form the dams and cataracts, wear themselves out leaping as arrows against all human and natural obstacles. Males and females arrive worn out at the end of their journey, the _frayère_ of fine sand where they are to lay their eggs, and the males heroically to spend the milt distilled from their blood.