The Journal of experimental zoology . ed graphi-cally in graph 4. It will be seen at once that some of the acids become lesstoxic as the H ion concentration is increased, formic lactic andacetic, for example, in the experiments with means that as the anions decrease in number the acid be-comes less harmful. In other cases, addition of HCl increasesthe toxicity, but only until it is equal to that of HCl of thesame Ph. Thus phthalic by itself is more toxic than HCl,but as ionization is depressed approaches it more closely; thatis, in graphic form, the curves are at first distinc
The Journal of experimental zoology . ed graphi-cally in graph 4. It will be seen at once that some of the acids become lesstoxic as the H ion concentration is increased, formic lactic andacetic, for example, in the experiments with means that as the anions decrease in number the acid be-comes less harmful. In other cases, addition of HCl increasesthe toxicity, but only until it is equal to that of HCl of thesame Ph. Thus phthalic by itself is more toxic than HCl,but as ionization is depressed approaches it more closely; thatis, in graphic form, the curves are at first distinct, but as Phis increased through the addition of HCl the phthalic approachesthe HCl curve and finally coincides with it. The same is trueof oxalic, benzoic, citric, acetic, propionic, butyric, valeric. Inthese cases, too, the anion must be toxic, since depression ofionization does away with the greater toxicity of the organicacid as compared with HCl of the same Ph. Since these acids 464 M. E. COLLETT \ H ^\ , M^ ^c /.. v. vA. 70 80 eo 100 Graph 6, H, I Effect upon toxicity at 20°C. of depressing ionization. (Para-moecium above and Euplotes below.) TOXICITY OF ACIDS TO CILIATE INFUSORIA 465 when in molecular form are not more toxic than HCl of the samePh, it seems provable that their molecules do not exert a toxicaction. The curves for Euplotes present a slightly different acids (oxalic, malonic, tartaric) become more toxic asionization is depressed. It will be noted that these are alldibasic acids. They are, however, so nearly like HCl that it isdifficult to draw any definite conclusions from the results. With TABLE 4Effect of depressing ionization Ph LENGTH OF LIFE IN MINUTES ACID Alone Plus HCl Paramoecium Euplotes • I II III I II III I II HI Formic Acetic 5122303045 21122 910 925 7J232
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectzoology, bookyear1919
