Abstract
The newly separated vegetative cell including that of the simpler animals such as the Protozoans is a minute mass of protoplasm in which there are at first no lacunae or breaks of any size, and the externally bounding layer is of extreme thinness and tenuity. The enlargement of expansion of the protoplast in this stage is chiefly one of formation or accretion of additional colloidal material and its hydration to a point where the water content is 50 to 500 times that of the dry weight of the included material.
My experiments of the last five years show that substances known to accelerate or facilitate growth also carry the hydration of living and dead cell masses and of pentosan-protein colloidal masses to a point beyond that which may occur in pure water. Such amino compounds, acidic and basic, as asparagin, alanin, glycocoll, phenyl-alanin and histidin, hydroxides and chlorides of potassium, sodium, magnesium and calcium in concentrations from 0.001 M. to 0.000,01 M. hydrochloric acid in the same range and water-soluble B yeast-vitamine Harris are included in the list and these are concentrations of biological occurrence. The enlargement of the cell in this stage must be due directly to imbibition and swelling as the vacuoles are not yet formed, although the fundamental unity of swelling and osmosis is to be recognized. In a second phase of growth, characteristic of plants and well illustrated by yeasts and bacteria, syneretic cavities appear in the plasmatic mass, and these known to the morphologist as vacuoles enlarge presumably by osmotic action, to such extent that their volume may comprise three fourths of the space of the cell.
Substances of four main groups, carbohydrates, proteins, soaps and lipoids which may be in the colloidal state of a reversible gel are entangled or intermixed in the protoplasmic mass.
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