Evolution / by Patrick Geddes and J. Arthur Thomson.

  • Patrick Geddes
Date:
[1911?]
Catalogue details

Licence: Public Domain Mark

Credit: Evolution / by Patrick Geddes and J. Arthur Thomson. Source: Wellcome Collection.

    101/264 (page 97)
    us notice some of the great acquisitions— bilateral symmetry, a head-brain, specialized sense-organs, a body-cavity, a segmented body, muscular feet, a renewable external armour, muscular jointed appendages, and so on. Or let us think of particular cases such as the extraordinary development of the re¬ spiratory system in insects, where ramifying tubes carry air to every nook and cranny of the body, so that the blood can hardly ever become impure, and a climax of vital activity is attained. The story of the evolution of Invertebrates is a succession of great achieve¬ ments. Among Vertebrates they were even greater. The Ascent of Vertebrates.—It is a profitable exercise to draw a long ascending slope, with perpendiculars dropped from various points to the base line, registering the evolutionary ascent of Vertebrate animals. What are the impressive facts ? (1) Life has been creeping or pressing upwards for many millions of years. (2) Great specializations occur at every level, but there is also beyond doubt a progressive differentiation and in¬ tegration. (3) This is particularly true of the nervous system, and is of course a con¬ dition and expression of the gradual increase of intelligent behaviour. Life becomes richer D