clairvoyance, of which the stork which takes its departure for the south four weeks earlier than usual knows no more than does the stag when before a cold winter he grows himself a thicker pelt than is his wont. On the one hand, animals have present in their consciousness a perception of the actual state of the weather; on the other, their ensuing action is precisely such as it would be if the idea present with them was that of the weather that is about to come. This they cannot consciously have; the only natural intermediate link, therefore, between their conscious knowledge and their action is supplied by unconscious idea, which, however, is always accurately prescient, inasmuch as it contains something which is neither given directly to the animal through sensual perception, nor can be deduced inferentially through the understanding. Most wonderful of all are the instincts connected with the continuation of the species. The males always find out the females of their own kind, but certainly not solely through their resemblance to themselves. With many animals, as, for example, parasitic crabs, the sexes so little resemble one another that the male would be more likely to seek a mate from the females of a thousand other species than from his own. Certain butterflies are polymorphic, and not only do the males and females of the same species differ, but the females present two distinct forms, one of which as a general rule mimics the outward appearance of a distant but highly valued species; yet the males will pair only with the females of their own kind, and not with the strangers, though these may be very likely much more like the males themselves. Among the insect species of the _strepsiptera_, the female is a shapeless worm which lives its whole life long in the hind body of a wasp; its head, which is of the shape of a lentil, protrudes between two of the belly rings of the wasp, the rest of the body being inside. The male, which only lives for a few hours, and resembles a moth, nevertheless recognises his mate in spite of these adverse circumstances, and fecundates her.