In order to understand these facts, apparently so inexplicable, we must look not only to the powerful influence of selection, but also to the zoögenic past of the species. With the insect the perfect form is always the last which it assumes, the outcome of all the previous metamorphoses. But the larval form, though actually transitory, must have been for a long time the permanent form, and it had different tastes and needs. At the present time there are still numbers of insects whose larval existence has a much longer duration than that of the so-called perfect insect (May-flies, cockchafers). There are even larvæ which reproduce themselves. Certain others, even though sterile, have not lost the maternal instinct. Thus at the time of the hatching of the nymphs the larvæ of the termites assist the latter to get rid of their envelope. It is therefore probable that, though now transitory, the larval forms of insects have formerly been permanent; they represent ancestral types, which evolution has by degrees metamorphosed into insects that we call perfect. The larvæ, now actually sterile, descend from ancestors which were not so, and in the larvæ of certain species the maternal instinct has survived the reproductive function.[31] This is doubtless the case with bees and ants; their workers must represent an ancestral form, having preserved the maternal fervour of its anterior state; the winged form, on the contrary, must be relatively recent. It even appears probable that in the republics of ants and bees the laborious workers may have succeeded, in a certain way, in getting rid of sexual needs which cause animals and even men to commit so many mad actions. With them the old maternal instinct has taken the place ceded to it by sexual instinct, and has become enlarged and ennobled. Their affection is no longer exclusively confined to a few individuals produced from their own bowels, but is shared by all the young of the association. In their sub-œsophagian ganglion one care takes precedence of all others--the care of rearing the young. This is their constant occupation and the great duty to which they sacrifice their lives. Maternal love, usually so selfish, expands with them into an all-embracing social affection. It is not impossible that a psychic metamorphosis of the same kind may one day take place in future human societies. It would even seem that the workers appreciate the faculty of reproduction all the more for being deprived of it. The queen bee, or rather the fertile female, who is the common mother of all the tribe, has every possible care lavished on her, and is publicly mourned when she dies. If she happens to perish before having young, and then cannot be replaced, the virgin workers despair of the republic; losing for ever “les longs espoirs et les vastes pensées,” they give way to an incurable and mortal pessimism.