Insects too, no less than men and stew-pans, always find their natural complement, though it mate the faultless with the faulty. Of this Minotaurus Typhœus furnishes a splendid example. The hazards of excavation present me with a curious couple, keeping house at the bottom of a burrow. The female calls for no special remark: she is just a handsome matron. But the male! What a sorry creature, what an abortion! The middle point of his trident is reduced to a mere spiked granule; those at the side come just level with the eyes, whereas in normal [[239]]subjects they reach the extreme point of the head. I measure the little beggar. His length is twelve millimetres[1] instead of eighteen,[2] the ordinary size. According to these figures, the dwarf is barely a quarter of the usual bulk.
In an earlier chapter of the present volume, I mentioned a magnificent male Minotaur who was obstinately refused by the consort whom my experiments had given him. The handsome horn-bearer did not leave the burrow; the other, despite my frequent interventions to restore harmony in the household, deserted her home nightly and sought to set up house elsewhere. I had to give her another partner; the one that I had thrust upon her did not suit her. If the male endowed with a generous stature and trident is often refused, how did the miserable specimen under consideration win the affections of his powerful mate? The unequal associations are doubtless to be explained among the Dung-beetles as among ourselves: love is blind.
Would this ill-assorted pair have bred? And would one part of the family have inherited [[240]]the noble dimensions of the mother and the other the stunted dimensions of the father? Not possessing, at the moment, a suitable apparatus, that is to say, a tall column of earth held between four planks, I lodged my Beetles in the longest test-tube among my entomological glass-ware, with moist sand and victuals at their disposal.
At first, all went according to rule, the mother digging and the father clearing away the rubbish. A few droppings were stored; then, on reaching the bottom of the test-tube, the couple pined away and died. The layer of sand was not deep enough. Before piling the food-sausage on top of an egg, the pair needed a shaft at least forty inches in depth, whereas they had only some eighteen inches to dig in.
This failure did not put an end to my list of questions. Where did that pigmy spring from? Was he the outcome of a special predisposition, transmitted by heredity? Or was he descended from another dwarf, who himself proceeded from a similar abortion? Was his deficiency merely an accident, which had nothing to do with heredity, an individual littleness not transmissible from father [[241]]to son? I incline to the theory of an accident. But what sort of accident? I can think of only one liable to diminish the size without injuring the type: I mean, a lack of sufficient food.
We argue thus: animals virtually take shape in a mould whose capacity may be extended in proportion to the amount of molten substance which the crucible pours into it. If this mould receives only the strictly necessary amount, the result is a dwarf. Anything beneath this minimum means death by starvation; anything above it, in doses which increase but are soon limited, means a prosperous life and a normal or slightly larger size. The bulk is decided by plus or minus quantities of food.
If logic be not a vain delusion, it is therefore possible to obtain dwarfs at will. All that we need do is to diminish the provisions to the lowest limits compatible with the maintenance of life. On the other hand, we cannot hope to make giants by increasing the ration, for a moment comes when the stomach refuses any excess of food. Natural necessities may be likened to a series of rungs of which the one at the top cannot be passed, [[242]]while it is quite practicable to stand higher or lower on those near the bottom.
First of all we must discover the regular ration. The majority of insects have none. The larva grows up amidst an indeterminate supply of victuals; it eats as it pleases and as much as it pleases, with no other check than its appetite. Others, those most richly endowed in maternal qualities such as the Dung-beetles and the Bees and Wasps, prepare definite rations of preserved food, neither too large nor too small. The Bee stores up in receptacles of clay, cement, resin, cotton or leaf-cuttings just the right amount of honey for a larva’s welfare; and, as she knows the sex of the future insects, she puts a little more at the service of the grubs that are to become females and will be slightly larger and a little less at the service of the grubs that are to become males and therefore will be smaller. In like manner, the Hunting Wasps dole out their game according to the sex of the nurslings.
It is now a long time since I did my utmost to upset the mother’s wise previsions by taking food from the wealthy grubs to increase the store of the poor. In this way I obtained [[243]]some slight modifications of size, to which the terms giant and dwarf could not, however, be applied; still less did I succeed in changing the sex, whose determination does not in any way depend upon the quantity of food supplied. The Bees and Wasps are not suited to my present purpose. Their grubs are too delicately constituted. What I want is sturdy stomachs capable of enduring severe ordeals. I shall find them in the Dung-beetles, notably in the Sacred Beetle, whose natural portliness will facilitate our appreciation of any change of bulk.
The big pill-roller calculates the food of her larvæ precisely: each grub has its loaf, kneaded into the shape of a pear. All these loaves are not strictly equal; some are larger and some smaller, but the difference is only minute. Perhaps these slight inequalities are connected with the sex of the nurslings, as among the Bees and Wasps; the females would receive the larger and the males the smaller rations. I did not take any steps to verify this theory. No matter: the fact remains that the Sacred Beetle’s pear is, in the mother’s opinion, a convenient individual ration. As for me, I can, if I please, alter [[244]]the size of the loaf, increasing or decreasing it at will. Let us first consider the decrease.