It seems clear, therefore, that the air which is put to this purpose is abstracted directly from the atmosphere, and that neither it nor the bubbles manufactured through it have ever been within the body of the insect. Moreover, if the little bubble-maker be thoroughly dried—which, according to Professor Morse, is a matter of difficulty—it will continue to secrete such spare fluid as it still has, but not the tiniest bubble is seen to issue with this. If set in a drop of water it struggles to the surface, and then goes through the same process of blowing bubbles as it has done when immersed in fluid of its own distilling. The result, however, is not the same, for the water will not hold the bubbles, which constantly disappear. Such, then, is the manner in which the frothy pool is made. What purposes does it answer? That of a pond, apparently, for it would appear that in their larval state these little frog-, or tree-hoppers, are to some extent aquatic insects. If kept dry and not allowed to renew their supply of fluid, their body shrivels, and before long they die. This is not through suffocation, since they can breathe air, by means of spiracles, in the ordinary way. If, however, they are examined closely, certain leaf-like appendages may be detected upon each side of the seventh and eighth segments of the abdomen, and Professor Morse suggests that these may be of the nature of branchiæ, or gills, enabling the insect to breathe, also, in water or fluid, by abstracting the air from it, after the manner of a fish, as some other aquatic larvæ do. “As many of these,” he says, “respire in two ways, either inhaling air through the spiracles, or by means of branchial leaflets, so _Aphrophora_ (for that is the classic name of our insect) may likewise utilise its branchial tufts for the same purpose. Thus we may see the reason for this bubble-blowing, since each fresh bubble added to the mass may aerate the fluid, so to speak, and thus secure at intervals a fresh supply of oxygen.”[36]