Through these apertures streams of workers are continually passing--some entering the cell to fetch the eggs, and others coming out with eggs carried carefully in their jaws. [Illustration: “WURBLES” OF ŒSTRUS.] [Illustration: EGG-HATCHING MACHINE.] Thus, as the reader will see, we have in Nature an exact analogy of Art, the Termite queen being confined within her cell exactly as is the hen within the coop. * * * * * BEING on the subject of eggs and egg-hatching, we will take another case in which Art has acknowledgedly followed Nature. We all know that eggs are developed into life by means of well-regulated heat, and that with birds the general rule is, that the needful heat is supplied by the parent bird, who sits upon them for a certain time, until the young birds make their appearance in the world. Under ordinary circumstances, the aid of the parent bird is quite sufficient; but when the progress of civilisation requires that the eggs of poultry should be hatched in numbers too great for the powers of the parent bird, Man has been fain to imitate Nature, and to invent machines whereby eggs can be hatched by artificial heat, regulated to the temperature of the hen’s body. Various as are these machines in detail, they are all alike in principle, and the right-hand figure of the accompanying illustration will give a fair idea of the method which is employed. A box is fitted up with trays, on which the eggs are arranged. At the bottom of the box there is the heat-producing apparatus, which can be regulated at pleasure. The trays of eggs can be moved from one part of the box to another, so as to insure the right amount of heat, and, if this process be only carefully carried out, the young chicks emerge from the eggs exactly as they would have done if the hen had sat upon them. This machine is sometimes called the Artificial Mother, and it is worthy of notice that it is no modern invention, the ancient Egyptians having used it more than three thousand years ago. * * * * * WITH regard to Nature, it would have been simple enough to give one illustration of a bird sitting on her eggs, but I have preferred to select a different subject, as more relevant to the question of artificial heat. There is an insect to which we have had several occasions of reference, namely, the Wurble-fly of the ox, scientifically known as _Œstrus bovis_.