Supplement Taf.20.

Title

Supplement Taf.20.

Description

Ten illustrations of different frogs and turtles.

ca. 1830

Artist

Oken (1779-1851)

Lorenz Oken (1779-1851) was a German physician and naturalist. One of his main works is the "Allgemeine Naturgeschichte für alle Stände" (General Natural History for all Estates), written during his time in Zurich. This important edition - probably the last work, in which one and the same author treats the whole natural history exhaustively - is a detailed and extensive reflection of the state of knowledge of that time. Here Oken has proceeded systematically: Starting with mineralogy, botany, the animal world to the most complex living being, the human being. The work is known among other things for his linguistically creative introduction of German terms, with which Oken in partly original way not only species and genera, but also the higher departments designated. Oken's main effort went on representation of an in itself coherent, all kingdoms of nature and their elements encompassing natural system.

Historical Description

The terms amphibians (Amphibia) or amphibians include all terrestrial vertebrates which, in contrast to amniotes, can only reproduce in water. In amphibians, individual development generally takes place via an egg laid in water, from which a gill-breathing larva living in the water hatches. This larva undergoes metamorphosis, at the end of which there is usually a lung-breathing adult individual that is capable of living outside of water. Due to their physiology, however, all amphibian species are at least bound to habitats with high humidity even in the adult stage. Many amphibians are nocturnal in order to protect themselves from predators and to minimize water loss through the skin. Amphibians are considered the most primitive group of terrestrial vertebrates, partly because they are dependent on water for reproduction, because some parts of their skeleton do not ossify and because of the relatively low efficiency of their lungs and cardiovascular system. This distinguishes them from the higher land vertebrates, including birds and mammals, which are collectively referred to as amniotes.