The evolution of sex / by Professor Patrick Geddes and J. Arthur Thomson.

  • Patrick Geddes
Date:
[1900]
Catalogue details

Licence: Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)

Credit: The evolution of sex / by Professor Patrick Geddes and J. Arthur Thomson. Source: Wellcome Collection.

    280/366 (page 260)
    200 THE EVOLUTION OF SEX. by observation ; a priori reasoning is here futile. The most serious criticism of Weismann's view is due to Maupas. Already we have noted his important result, that conjugation is essential to the youth of the species. Without this incipient sexual reproduction, the individuals in the course of numerous successive asexual generations grow old. The nucleus degen¬ erates, the size diminishes, the entire energy wanes, the senility ends in death. Maupas believes that all organisms are fated to suffer decay and death, and protests strongly against Weis¬ mann's theory that death begins with the Metazoa. It must be noted, however, that in natural conditions the conjugation, prohibited in Maupas's experiments, occurs when it is wanted, and the life flows on. Furthermore, conjugation has not been shown to occur in many Protozoa. It seems therefore more warrantable to insert Maupas's result as a saving clause to Weismann's doctrine, than to regard it as contra¬ dictory. The conclusion at present justifiable, is that Protozoa not too highly differentiated, living in natural conditions where conjugation is possible, have a freedom from natural death. To this must then be added the demonstrated saving clause, that in ciliated infusorians, ccmjugation, which here means an exchange of nuclear elements, is the necessary con¬ dition of eternal youth and immortality. Accepting then, with an emphasised proviso, the general conclusion that most, if not all, unicellular organisms enjoy immortality, that in being without the bondage of a body they are necessarily freed from death, we ])ass to consider the second question, What does the death of the higher and multi¬ cellular organisms really involve? If death do not naturally occur in the Protozoa, it is evident that it cannot be an inherent characteristic of living matter. Yet it is universal among the multicellular animals. Death, we may thus say, is the price paid for a body, the penalty its attainment and possession sooner or later incurs. Now, by a body is meant a complex colony of cells, in which there is more or less division of labour, where the component units are no longer, like the Protozoa, in possession of all their faculties, but through division of labour have only restricted functions and limited powers of self-recuperation. Like Maupas's isolated family of infusorians, the cells of the body do not conjugate with one another ; and though they divide and redivide for a season, the life eventually runs itself out.