. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. PERMEABILITY OF ARBACIA EGG TO AMMONIUM SALTS 175 B. N / > FIG. 9. Swelling curves for Arbacia eggs in solutions of ammonium formate (X), acetate (A), propionate (©), butyrate (•) and valerate (D) ; pH Solid lines, M/2 solutions; broken lines, M/2 solutions in bicarbonate-free sea water. (See Footnote 1 concerning pH values used.) Ill If the rate of entrance of free acid into the cell is the most impor- tant factor in influencing the rate of penetration of the salt, then it would be expected that the pH of the soluti
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. PERMEABILITY OF ARBACIA EGG TO AMMONIUM SALTS 175 B. N / > FIG. 9. Swelling curves for Arbacia eggs in solutions of ammonium formate (X), acetate (A), propionate (©), butyrate (•) and valerate (D) ; pH Solid lines, M/2 solutions; broken lines, M/2 solutions in bicarbonate-free sea water. (See Footnote 1 concerning pH values used.) Ill If the rate of entrance of free acid into the cell is the most impor- tant factor in influencing the rate of penetration of the salt, then it would be expected that the pH of the solution, which determines the relative concentrations of free acid and ammonia, would have a very important influence upon the swelling process. This proves to be the case. In general the increase in volume of the cells tends to become more rapid as the pH is lowered, down to about , and to become progressively slower as the pH is increased above The swelling of the eggs in a solution of ammonium acetate at pH is almost imperceptible (Fig. 2), while at pH (Fig. 3)—an acidity which is not in itself markedly injurious—they increase in size so rapidly that cytolysis occurs within five or six minutes. A striking illustration of this effect of pH in changing the amount of free acid, and consequently the rate of swelling of the Arbacia eggs, is given in experiments such as that represented in Fig. 8. Here ammonium acetate solutions were used and the pH varied, in small steps, between and There is no exception to the orderly increase in rate with decrease in pH. The experiment has been repeated several times, always with the same re- sults. Similar, though less extensive, observations have been made with each of the other salts (Figs. 5, 6, 7). The only essential difference between them lies in the spread of the three curves, which becomes less and less as the ease of penetration of the free acid involved increases, until finally, with the valerate, the curv
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
