Regeneration from a physico-chemical viewpoint / by Jacques Loeb.

  • Jacques Loeb
Date:
1924
Catalogue details

Licence: In copyright

Credit: Regeneration from a physico-chemical viewpoint / by Jacques Loeb. Source: Wellcome Collection.

    24/166 (page 8)
    lasts. This is not strictly correct, since the new shoots formed also contain chlorophyll. But the experiment is terminated before this can cause an appreciable error. It can be shown that the dry weight of shoots or roots regenerated by a leaf or stem is (under equal conditions and in equal time) in direct proportion to the mass of leaves or stems in which regeneration occurs; and this simple relation will be designated briefly as the mass relation. The reader will notice that the weight of shoots and roots pro¬ duced by a leaf or stem is used as a measure of the rate of growth of the shoots and roots. The proportionality between mass of leaves or stems and the mass of shoots and roots produced by them no longer need to hold as soon as the growth of shoots and roots is no longer exclusively or predominantly a function of the assimilating activity of the leaf or stem. Whether or not the mass relation is identical with the law of mass action may remain undecided as far as the contents of this book are concerned. The mass relation may certainly be at first the expression of the mass law, since the first anlagen of shoots and roots are equal regardless of the mass of the leaf or stem where the regeneration occurs. The mass of material diffusing into each anlage will increase with the mass of the leaf or stem (provided the light is not excluded), and the concentration of the solutes of the sap in each anlage will as a consequence increase in proportion with the mass of the leaf or stem in which the regeneration occurs. It is quite possible that the growing points of the young shoot will remain small and not vary materi¬ ally in size during the first growth, and in this case the mass relation will remain identical with the mass law. But if the internodes of the new regenerated shoot grow in thickness the mass of growing cells in a large regenerated shoot will be greater than that in a smaller shoot, and in this case the mass relation may no longer be identical with the mass law. For this reason we shall only speak of the mass relation and not of the mass law. The mass relation, that is, the fact that the mass of shoots and roots regenerated varies in proportion with the mass of the leaf or stem where the regeneration occurs, is sufficiently simple and rationalistic to serve as a guide in the maze of the phenomena of regeneration.