In connection with such a slaughter for the benefit of a progeny that will never exist, I may mention observations relating to a quite different order of phenomena. There are many creatures that kill and devour their progeny. Not infrequently rabbits kill and devour all their progeny, or leave them to die without food or care. Sometimes the culprits are young rabbits without experience; but this aberration of instinct is also met with in old rabbits, which once and for all have contracted the habit of abandoning or eating their young. Some females of other species of mammals and of birds have often been surprised in the act of deserting or of killing their offspring. Perversion of sexual instinct is frequent enough amongst animals. Huber[40] states that when male ants have a lack of females they ravish the workers, the attacks being fatal, as the sexual organs are incompletely developed and functionally incapable. Abnormal pairing has also been observed in the stag-beetle of the genus _Lucanus_, in bees, and, above all, in cockchafers.[41] Higher animals, such as dogs, furnish analogous examples of sexual perversion. Onanism is well known amongst mammals. It is frequent among monkeys in menageries, and also in rutting stags, the latter discharging the seminal fluid by friction with trees. Stallions and mares have often been observed in the act of satisfying their sexual appetites by abnormal means. There are several other species (dogs, bears, chamois, elephants, parrakeets, etc.,) which resort to onanism.[42] These disharmonious instincts do not in the least cause the death of the animals that manifest them. But there exist in nature instinctive aberrations much more dangerous. Who has not seen in the summer numerous insects gathered round lamps and candles, attracted by the light? Among these are Coleoptera, Neuroptera (_Phryganea_), Ephemera, and, most frequently of all, small nocturnal Lepidoptera. After flying round and round the light several times, they singe their wings and die in numbers. This instinct is so constant and so developed amongst many of these insects, that it has been used against them for their own destruction. Thus amongst the means advocated for destroying a moth, _Botys sticticalis_, the caterpillars of which devour cereals and beetroot,[43] is the lighting of numerous fires in the fields. The moths, attracted by the light, fall in the flames and die in quantities.