MEMOIR OF SWAMMERDAM. 23 



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 pheno- 

 mena 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, con- 

 taining nothing but a watery ichor, but they soon 

 become more matured, and the wings may be ob- 

 served in them folded together. When full grown, 

 all the varieties of colour and painting which dis- 

 tinguish 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 sin- 

 gular 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 em- 

 ployed 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 resist- 

 ance made by the stationary mass behind during the 



