His classification of insects differs very materially from those now in use. The characters of his four classes he derives from the state in which each insect appears after its birth, and those through which it passes before attaining its entire development. In the first he places all those which issue from the egg with nearly the same form as that which they have at the period of their full growth; such as spiders, slugs, leeches, &c. In the second are included those which, like the grashopper, issue with six feet, and some time after cast off the covering under which the wings were concealed. These insects run or leap with agility in their first stage, which is not the case with those of the next class. To the third are referred insects which undergo greater changes, such as caterpillars, and which proceed from the egg in the state of a worm, remain in that state for some time, cast off their hairy covering, assume the form of a chrysalis, when they become motionless, and finally emerge in a winged state. The fourth class consists of such as, like the common fly, on changing the form under which they issued from the egg to assume that of a worm, do not cast their covering, but become separated from it, while it remains and forms a shell or egg-like investiture, in which the insect remains in the pupa state until it finally emerges with wings. The history of Swammerdam must excite our sympathy and commiseration; but that, as some have alleged, he lost his reason towards the end of his life, and became subject to mania, arising from religious melancholy, no one who has any share of that piety which he evinced will feel disposed to admit. Although he lived in misery, the close of his life was perhaps more enviable than that of many who have gone smiling to their final rest; and it is well for those who, before the period arrives when as the tree falls so it must lie, can like him become truly sensible of the vanity of all earthly pursuits, even although after death they should be pointed out as the victims of a distempered imagination. FOOTNOTES: [H] Reaumur, Histoire des Insectes, tome i. p. 28. RAY. _Account of the Life and Writings of Ray._