United States or Saint Martin ? Vote for the TOP Country of the Week !
It is a remarkable fact, as he justly observes, that the angiospermous exogens, which comprise four-fifths of living plants a division to which all our native European trees, except the Coniferae, belong, and which embrace all the Compositae, Leguminosae, Umbelliferae, Cruciferae, Heaths, and so many other families are wholly unrepresented by any fossils hitherto discovered in the Primary and Secondary formations from the Silurian to the Oolitic inclusive.
Cannot a man work in wood without knowing all about endogens and exogens, or must he attend Professor Gray's Lectures before he can be trusted to make a box-trap? If my horse casts a shoe, do you think I will not trust a blacksmith to shoe him until I have made sure that he is sound on the distinction between the sesquioxide and the protosesquioxide of iron?"
If so, the limitation of this more ancient flora, represented by so many genera and species, to the gymnospermous and cryptogamous orders, and the absence or extreme rarity of plants of higher grade, lead us naturally to speculate on the theory of progressive development, however difficult it may be to avail ourselves of this explanation, so long as we meet with even a few exceptional cases of what may seem to be monocotyledonous or dicotyledonous exogens.
The Ichthyosaurus, Pterodactyl, and Mosasaurus were of coeval date with the oak, the walnut, and the fig. Speculations have often been hazarded respecting a connection between the rarity of Exogens in the older rocks and a peculiar state of the atmosphere.
Cannot a man work in wood without knowing all about endogens and exogens, or must he attend Professor Gray's Lectures before he can be trusted to make a box-trap? If my horse casts a shoe, do you think I will not trust a blacksmith to shoe him until I have made sure that he is sound on the distinction between the sesquioxide and the protosesquioxide of iron?"
Cryptogamous acrogens: Acrogens: Mosses, equisetums, ferns, lycopodiums Lepidodendra. Dicotyledonous gymnosperms: Gymnogens: Conifers and Cycads. Dicotyledonous Angiosperms: Exogens: Compositae, leguminosae, umbelliferae, cruciferae, heaths, etc. All native European trees except conifers. Monocotyledons: Endogens.
Phanerogamic plants in their lowest groups of gymnosperm exogens then begin to appear in the Devonian conifers, gradually followed by cycads. And it is not till Cainozoic times that we have the endogenous grasses and palms and angiospermous exogens.
Word Of The Day