Page:Popular Science Monthly Volume 10.djvu/271

This page has been validated.







By Professor C. H. HITCHCOCK,


THE surmises and discoveries of the past twenty years have established the fact of the existence of life throughout the entire series of stratified rocks known to geologists, both sedimentary and metamorphic. When Principal Dawson published his description of the Eozoön in the Laurentian foundations, he was led to suggest the adoption of the term Eozoic in place of Azoic for all the ages older than Paleozoic, since, if life existed in the oldest formation, it must have continued to flourish in the following æons, even though evidences of its presence had not then been accumulated. Time has approved of this sagacious anticipation, and we can now maintain with serene confidence that the four great Eozoic periods—Laurentian, Labrador, Atlantic or Montalban, and Huronian—were all enlivened by the existence of both vegetable and animal life. And Eozoic life had its peculiar characteristics just as much as the Silurian or Carboniferous. This life has appeared in consonance with the general principles of evolution as announced by our most learned sages. The earliest organic forms were the simplest in their structural relations; and they flourished through untold ages. The world was no longer young when the organic scheme permitted the growth of Cambrian trilobites and mollusca. More than half of geological time had passed away during the reign of protozoans and fungi. This suggests the enunciation of a general principle, in perfect agreement with the doctrines of evolution: the simpler the predominating forms of life the longer the period. In the beginning of Nature's operations, time was the element of which lavish use was made. It has grown more valuable as the ages have passed on, and the perfected type of organic development in our period grudges the loss of a single moment of it.

The evidences of the earlier forms of life naturally divide them-