The body : an introduction to physiology / by Ronald Campbell Macfie.

  • Ronald Campbell Macfie
Date:
[1927]
Catalogue details

Licence: In copyright

Credit: The body : an introduction to physiology / by Ronald Campbell Macfie. Source: Wellcome Collection.

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    at least—in complicated chemical formulae and equa- tions. On this point the verdict of science is unequi- vocal and categorical. Science maintains that living organisms are chemical products of warm mud and atmospheric gases, that when the crust of the cooling and sterile earth attained a suitable temperature, atoms of carbon, hydrogen, oxygen, and nitrogen combined, under the ordinary laws of chemical affinity, to form gigantic molecules of the vital substance “ proto- plasm ”—“ a self-generating reproductive carbonaceous jelly ” whose complicated chemical constituents, re- acting inter se, and with their environment, give rise to metabolism, assimilation, reproduction, and the other functions called ‘ vital ’ by which we define living things. This “ primordial flux ” and its results were due simply to chemical affinity and chemical com- binations, v/ith consequent chemical processes in a complex matrix set in a complex and variable environ- ment. A wonderful flux, certainly; but “ who,” asks Tyndall, “ will set limits to the possible play of mole- cules in a cooling planet?” According to this theory, the first little speck of protoplasm was chemically constituted in such a way that it not merely multiplied by division or budding, but coincidently varied and mutated, so that eventually, by selection of variants and mutations, various species of unicellular organisms came into being. In time were evolved variant cells, whose buds—arranged in certain definite orientation and form—maintained chemical and structural connection with each other, and became lowly multicellular organisms; and finally the germ-cells of these lowly multicellular organisms evolved, by a process of variation and selection, into the wonderful ovum of man. Heredity, evolution, and variation led to man, and still to-day in man and in ail living beings we see reproduction, variation, and evolution at play.