The gospel of evolution / by Professor J. Arthur Thomson.

  • Thomson, J. Arthur (John Arthur), 1861-1933.
Date:
[1925]
Catalogue details

Licence: In copyright

Credit: The gospel of evolution / by Professor J. Arthur Thomson. Source: Wellcome Collection.

    59/218 (page 55)
    Animals, on the other hand, feed at a high chemical level, on the carbohydrates (e.g., starch and sugar), fats, and proteins (<e.g., gluten, albumin, casein) which are manufactured by other animals, or, to begin with, by plants. Their cells have not cellulose walls, nor in most cases much wall of any kind, and motility in the majority is unrestricted. THE BEGINNINGS OF LAND PLANTS. It is highly probable that for long ages the waters covered the earth, and that all the primeval vegetation consisted of simple Flagel¬ lates in the universal Open Sea. But contrac¬ tion of the earth’s crust brought about elevations and depressions of the sea-floor, and in places the solid substratum was brought near enough the surface to allow the floating plants to begin to settle down without getting out of the light. This is how Professor Church pictures the begin¬ ning of a fixed vegetation—a very momentous step in evolution. It was perhaps among this early vegetation that animals had their first successes. As the floor of the sea in these shallow areas was raised higher and higher there was a beginning of dry land. The sedentary plants already spoken of were the ancestors of the shore seaweeds, and there is no doubt that when we go down at the lowest tide and wade