This question of compatibilities is illustrated very strikingly by the case of the worker-bee. There is as yet no purely Mendelian interpretation of this case, Mendel's own laborious work upon heredity in bees having been entirely lost, and practically nothing having been done since. Yet, as will be evident, the main argument of Geddes and Thomson leads us to a similar interpretation of this case in terms of compatibility. The worker-bee is an individual of a most remarkable and admirable kind, from whom mankind have yet a thousand truths to learn. She is distinguished primarily by the rare and high development of her nervous apparatus. In terms of brain and mind, using these words in a general sense, the worker-bee is almost the paragon of animals. The ancients supposed that the queen-bee was indeed the queen and ruler of the hive. Here, they thought, was the organizing genius, the forethought, the exquisite skill in little things and great, upon which the welfare of the hive and the future of the race depend. But, in point of fact, the queen-bee is a fool. Her brain and mind are of the humblest order. She never organizes anything, and does not rule even herself, but does what she is told. She is entirely specialized for motherhood; but the thinking, and the determination of the conditions of her motherhood, are in the hands of other females, also highly specialized, and certainly the least selfish of living things--_yet themselves sterile, incapable of motherhood_. Observe, further, that these wonderful workers, so highly endowed in terms of brain, are amongst the children of the queen, herself a fool; and that it was the conditions of nourishment, the conditions of environment or education, which determined whether the young creatures should develop into queens or workers, fertile fools or sterile wits. We have here an absolute demonstration that environment or nurture can determine the production of these two antithetic and radically opposed types of femaleness. Now, amongst the bees, this high degree of specialization works very well. How old bee-societies are we cannot say. We do know, at any rate, that bees are invertebrate animals, and therefore of immeasurable antiquity compared with man. No one can for a moment question the eminent success of the bee-hive; and that success depends upon the extreme specialization of the female, so as in effect to create a third sex. Further, we know that nurture alone accounts for this remarkable splitting of one sex into two contrasted varieties.