. Dawn of life: being the history of the oldest known fossil remains, and their relation to geological time and to the development of the animal kingdom. Paleontology; Eozoon; Life. IGO THE DAWN OF LIFE. sometimes preserved merely by infiltration with cal- cite or dolomite^ and in tMs case it is most difficult to make out their minute structures. Often they appear merely as concentrically laminated masses which, but. Fig. 45. Ccenostroma—Guelph Limestone, Upper Silurian, from a specimen collected by Mr. JFeston, showing the canals. (a.) Surface AVitli canals, natural size, {b.) Vertical sectio
. Dawn of life: being the history of the oldest known fossil remains, and their relation to geological time and to the development of the animal kingdom. Paleontology; Eozoon; Life. IGO THE DAWN OF LIFE. sometimes preserved merely by infiltration with cal- cite or dolomite^ and in tMs case it is most difficult to make out their minute structures. Often they appear merely as concentrically laminated masses which, but. Fig. 45. Ccenostroma—Guelph Limestone, Upper Silurian, from a specimen collected by Mr. JFeston, showing the canals. (a.) Surface AVitli canals, natural size, {b.) Vertical section, natural size, (c.) The same magnified, showing canals and laminae. for their mode of occurrence, migrht be resrarded as mere concretions. In other cases the cell-walls and pillars are perfectly silicified, and then they form beau- tiful microscopic objects^ especially when decalcified with an acid. In still other cases, they are preserved like Eozoon, the walls being calcareous and the cham- bers filled with silica. In this state when weathered or decalcified they are remarkably like Eozoon, but I have not met with any having their minute pores and tubes so well preserved as in some of the Laurentian fossils. In many of them_, however, the growth and overlapping of the successive amoeba-like coats of sar- code can be beautifully seen, exactly as on, the surface of a decalcified piece of Eozoon. Those in my collec- tion which most nearly resemble the Laurentian speci-. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Dawson, John William, Sir, 1820-1899. London, Hodder & Stoughton
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Keywords: ., bookcentury1800, bookdecade1870, booksubjectpaleontology, bookyea
