In the hermaphrodism of echinoderms, of fish, there is never auto-fecundation; either the sexual products meet outside the animals, which have neither copulating organs, nor a related genital life; it is a simple growth of germs; or, in a more complex phase the individuals have exterior male organs, and female organs, but they can not use them without the aid of another individual acting either as male, or as female. Here a new distinction is imposed: either the animal will be successively male, and then female; or it will be both at once. This union of the two sexes seems useless, according to human logic, when the two genital glands ripen at different seasons; one understands it better when the reciprocal fecundation is simultaneous, since this doubles the number of females and better assures the conservation of the specie. One must set aside the idea of pleasure. Apart from the fact that we can judge it only by a very distant and even dubious analogy considering the difference between the nervous systems of man and mollusk, one must set it aside as useless. Pleasure is a result not an aim. In most animal species coition is but a prelude to death, and often love and death work their supreme act in the same instant. Copulation of insects is suicide: would it be reasonable to consider it as produced by a desire to die? One must dissociate the idea of pleasure and the idea of love, if one wants to understand anything of the tragic movements which perpetually beget life at the expense of life itself. Pleasure explains nothing. People might simply be commanded to die as a means of reproduction, they would obey with the same eagerness: this is observed even in humanity. Dithyrambs on pleasure would be misplaced apropos of the mutual ticklings of two snails on a vine-leaf; the subject is rather uncomfortable.
Note then two helices, both bisexual, fulfilling exactly the biblical phrase: "he created them male and female"; their genital organs are very well developed; the penis and oviduct opening into a vestibule, which in the act of copulation unbellies itself in part, so that the penis and vagina come in touch with the orifice; mutual intromission takes place. A third organ comes from the vestibule, without analogy in superior animals; it is a little pocket containing a small stiletto, a jewelled dagger; it is an excitative organ, the needle to prick up desires. These beasts who have prepared for love by fasting, by long rubbings, by whole days of close pressure, finally come to a decision, the swords come out of their scabbards, they conscientiously stab each other, this causes the penis to rise from its sheath; the double mating is accomplished.