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.

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    of life. For although the individual A dis¬ appears in giving rise to B and C, its daughter- cells, we can hardly speak of death when there is nothing left to bury. On the one hand, we reach the idea that death was the price paid for a body; on the other hand, we see that in the simplest forms of life immortality has not even yet been pawned for love. The Origin of Sex.—In many of the uni- cellular organisms there is a kind of sexual reproduction, in the sense that two cells fuse to become one, just as ovum and spermatozoon do in higher creatures. In many cases, more¬ over, the two cells which fuse are dimorphic, as is well illustrated in the bell-animalcule, Vorticella, where a small, active, free-swim¬ ming (we may say, male) cell unites with a fixed individual of full size, which may be called female. This is one line of approach to the origin of sex, and it may be noted that the male and female cells illustrate the anti¬ thesis we have already discussed between relatively more anabolic and relatively more katabolic types. The next stage in the problem is to account for the familiar fact that in almost all organisms with bodies there are special reproductive ceils, or germ-cells—ova and spermatozoa— quite distinct from the ordinary body-cells.