MEMOIR OF SWAMMERDAM. 23 
purpose of inflating tlic 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, ore 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 hisheingunacquainted, 
as appears from the statement just made regarding 
their food, until 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 
