"The fact, of course familiar to every beginner in biology, is that the crystal is only incorporating and not excreting anything, whereas the living matter is always excreting as well as assimilating. This one-sided metabolism--if it can be dignified with that term--is indeed characteristic of the crystal, but it is at no time characteristic of the living organism. The organism, whether truly growing or only in metabolic equilibrium, is constantly taking up material to replace effete material, is replenishing because it has previously displenished itself or cast off material. The resemblance between a so-called 'growing' crystal and a growing organism is verily of the most superficial kind." And Professor Fraser Harris concludes his article thus:-- "Between the living and the non-living there is a great gulf fixed, and no efforts of ours, however heroic, have as yet bridged it over." NOTE C.--OLD AGE We know that as vitality diminishes the bodily deterioration called old age sets in, and that a certain amount of deterioration results in death; but it turns out, on systematic inquiry, that old age and death are not essential to living organisms. They represent the deterioration and wearing out of working parts, so that the vivifying principle is hampered in its manifestation and cannot achieve results which with a younger and healthier machine were possible; but the parts which wear out are not the essential bearers of the vivifying principle; they are accreted or supplementary portions appropriate to developed individual earth life, and it does not appear improbable that the progress of discovery may at least postpone the deterioration that we call old age, for a much longer time than at present. Emphasis on this distinction between germ cell and body cell, usually associated with Weismann, seems to have been formulated before him by Herdman of Liverpool.