Origination of Self-Generating Matter and the Influence of Aridity upon Its Evolutionary Development
| Autor: | D. T. MacDougal |
|---|---|
| Rok vydání: | 1909 |
| Předmět: | |
| Zdroj: | The Journal of Geology. 17:603-622 |
| ISSN: | 1537-5269 0022-1376 |
| DOI: | 10.1086/621663 |
| Popis: | Any attempt at an interpretation of a desert landscape, with its diversity of forms, isolation of individuals, and scarcity of organic matter in the soil, leads inevitably to a consideration of the theoretical conditions which would be necessary in the origination of the physical basis of life, its development into organisms known to us in the living and fossil state, and also of the possibilities of the occurrence of a re-generation at the present time. From almost every excursion which the biologist has made into this inviting field of speculation on which he has called to his aid various extreme or unusual intensities of the factors to be taken into account, he has been ruthlessly recalled by the geological historian with the reminder that the general composition of the atmosphere, its pressure, the temperatures, and other conditions prevalent on the earth's surface were uniform and continuous with those now encountered and not widely different, in their total departure, in any stage of terrestrial development in which life might have originated. Now we are not able to discover that living or self-generating matter is actually being formed anew on the earth's surface at the present time, and in the absence of positive evidence we are compelled to say that all life now in existence must have descended from forms which had their ultimate origin in other times and under other conditions than those now prevalent. A consideration of the phyletic aspects of fossil and living forms of plants yields but little, which might serve as an indication of the conditions under which the earlier forms developed. Even the earliest remains include such advanced types as the ferns and cycads. The amount of progress represented by the derivation of the gametopetalous seed-plants from these, in comparison with the preceding |
| Databáze: | OpenAIRE |
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