Abstract
Earlier researches on hydration effects were concerned chiefly with gelatine as taken to represent the action of living matter. The effort to obtain results directly applicable to plant protoplasm, led to a consideration of chemical composition, solubility and other properties as a consequence of which mixtures of agar and protein were found to give hydration reactions so nearly comparable to those of living cell-masses that their study yields extremely useful facts and numerous stimulating suggestions.
The importance of the acids or of the hydrogen ion concentration in swelling had become apparent very early in the brief history of this subject. Workers using botanical material have dealt with this matter chiefly by the use of hydrochloric, and with acetic, citric and malic acids, and with salts of biological occurrence and concentrations. Although much careful work has been done some doubt still exists as to the part which the acid radicle may play in the complex system of substances always present in the protoplasmic colloid. A study of the action of these acids and of organic acids and of their amido compounds promised comparisons that might be of importance in this matter, and a series of measurements were carried out in the equable temperature chambers of the Coastal Laboratory August to November, 1918.
Three groups of substances were selected for these tests; (1) succinic acid and its amido-compound, a amino-succinic or aspartic, which are dibasic, and its amide, asparagin, which is monobasic; (2) acetic acid and a amino-acetic acid or glycocoll, which are monobasic; (3) propionic acid and a amino-propionic acid or alanin, also monobasic.
The swellings of sections of agar and a mixture of 8 parts agar and 2 parts oat-protein are selected for discussion at the present time.
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