purpose of inflating the minute vessels. He also traced the different states of Dragon-flies, from the egg to the imago, from examples which he observed in the river Loire; and noticed most of the curious phenomena which attend their metamorphoses. He states, that the ovaries of these insects perfectly agree with those of fish, especially that of the herring, and consist, in like manner, of numerous eggs, which are of an oblong figure. When the vermicle, or young larva, has grown a little, four membranous buds or follicles, like flower-cups, are observed to spring out of the body near the end of the thorax; if opened at an early period, these are found to be mere bags, containing nothing but a watery ichor, but they soon become more matured, and the wings may be observed in them folded together. When full grown, all the varieties of colour and painting which distinguish the perfect insect, become transparent through the skin. The food of these larvae, he says, is soft mud, and the fine earthy substance in which they live. Although Swammerdam figures the singular mask of one of these creatures, he does so in an imperfect manner, and from his being unacquainted, as appears from the statement just made regarding their food, with their carnivorous nature, he had formed no accurate notion of its use. Neither does he appear to have detected the singular means employed to effect movement through the water, which is now known to be by the alternate absorption and ejection of that fluid from the abdomen, the resistance made by the stationary mass behind during the
