Our subject belongs to the class Insecta, which is mainly characterized by breathing air usually through a very complicated system of air-tubes. These tubes (Fig. 1), which are constantly branching, and almost infinite in number, are very peculiar in their structure. They are formed of a spiral thread, and thus resemble a hollow cylinder formed by closely winding a fine wire spirally about a pipe-stem, so as to cover it, and then withdrawing the latter, leaving the wire unmoved. Nothing is more surprising and interesting, than this labyrinth of beautiful tubes, as seen in dissecting a bee under the microscope. I have frequently detected myself taking long pauses, in making dissections of the honey-bee, as my attention would be fixed in admiration of this beautiful breathing apparatus. In the bee these tubes expand into large lung-like sacks (Fig. 2, _f_), one each side of the body. [Illustration: Fig. 2. _Respiratory Apparatus of Bee, magnified.--After Duncan._] Doubtless some of my readers have associated the quick movements and surprising activity of birds and most mammals with their well-developed lungs, so, too, in such animals as the bees, we see the relation between this intricate system of air-tubes--their lungs--and the quick, busy life which has been proverbial of them since the earliest time. The class Insecta also includes the spiders, scorpions, with their caudal sting so venomous, and mites, which have in lieu of the tubes, lung-like sacks, and the myriapods, or thousand-legged worms--those dreadful creatures, whose bite, in case of the tropical centipedes or flat species, have a well-earned reputation of being poisonous and deadly. The class Insecta does not include the water-breathing Crustacea, with their branchiæ or gills, nor the worms, which have 110 lungs or gills but their skin, if we except some marine forms, which have simple dermal appendages, which, answer to branchiæ. ORDER OF THE HONEY-BEE.