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.

    91/264 (page 87)
    But out of this weakness—if weakness- strength arose, the strength of animals with a body. Beginning of Death.—In a startling phrase—the immortality of the Protozoa— Weismann called attention to the fact that unicellular organisms are not subject to natural death in the same degree as higher animals are. They may be killed, of course, in many ways, but they do not normally die. Even against microbic infection many of them seem proof; they digest the virulent intruders, as do the phagocytes which form our body¬ guard. But the point is, that in natural conditions, where inter-crossing, for instance, is readily feasible, they appear to be exempt from that natural death which in the higher organisms is due to the slow mounting-up of physiological arrears. How is it that these simple pioneer organ¬ isms are exempt from the penalty all other flesh is heir to ? The answer is twofold. On the one hand, being relatively very simple, in a strict sense without a “ body ”—they are able to sustain with persistent success the vital equation between waste and repair. On the other hand, their common mode of repro¬ duction, by dividing into two or more units, is inexpensive and not attended with any loss