the investigations relating to insects, which compose the greater portion of the work, there is a lengthened account of the snail, (Helix,) explaining its anatomy, mode of propagation, &c., a treatise on the generation of the frog, on the anatomy of the cuttle-fish, &c.
The manner in which Swammerdam treats of the arrangement of insects into classes, is, as might he expected, not a little defective. But he was certainly the first that assumed metamorphosis as the basis of a natural system, and in so doing, merits high approbation. He referred all to four classes of metamorphosis, which, translated into the modern language of entomology, may be expressed as follows:
| 1. | No metamorphosis. | The animal changes its skin, but preserves its primitive form; as in Aranea, Pulex, Myriapodes. In short the Aptera of Linnæus. |
| 2. | Metamorphosis. a. | Incomplete. Animal active during its whole life: at first without wings; acquires rudiments of them in the nymph, and they become complete in the imago. Neuroptera, Orthoptera, Hemiptera. |
| b. | Complete. Animal immoveable in the nymph state, but possessed of limbs. Hymenoptera, Coleoptera, Lepidoptera. | |
| c. | Coarctate. Animal without limbs, and incapable of motion in the nymph state. Diptera. |
The science of insect anatomy, as well as of some other tribes of animals related to insects, may almost
