The Germ-plasm : a theory of heredity / by August Weismann ; translated by W. Newton Parker and Harriet Ronnfeldt.

  • Weismann, August, 1834-1914.
Date:
1893
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Licence: Public Domain Mark

Credit: The Germ-plasm : a theory of heredity / by August Weismann ; translated by W. Newton Parker and Harriet Ronnfeldt. Source: Wellcome Collection.

Provider: This material has been provided by Royal College of Physicians, London. The original may be consulted at Royal College of Physicians, London.

    474/510 (page 450)
    SUMMARY AND CONCLUSION. ALL the phenomena of heredity depend on minute vital units which we have called ' biophors,' and of which living matter is composed : these are capable of assimilation, growth, and mul- tiplication by division. We are unacquainted with the lowest conceivable organisms, and do not even know if they still exist. But they must at any rate have done so at some time or other, in the form of single biophors, in which multiplication and trans- mission occurred together, no special mechanism for the purposes of heredity being present. A higher order of beings would then have been constituted by those organisms which were composed of a large number of similar biophors. Of these also we have no actual knowledge based on observation, but must suppose that they too required no special apparatus for the processes of transmission ; for a reproduction by binary fission must result in two perfectly corresponding halves, each containing similar biophors, and each of which, simply by the multiplication of these units, is able to give rise to a complete organism exactly like the parent. This simple form of transmission must have become modified when the biophors underwent differentiation in connection with a division of labom, and became combined in various ways to form the body of the organism. These two kinds of hypothetical beings might be respectively distinguished as homo-biophorids and hetero-biophorids. Not only might a firmer cortex and softer internal substance be present in the latter, but a differen- tiation into anterior, posterior, dorsal, and ventral regions might occur ; several layers of the body substance, diffisring structurally and functionally from one another, might also be developed, to- gether with motile and non-motile processes—such as flagella, cilia, spines, and hooks,—like those present amongst the Infu-