The Journal of experimental zoology . c [Valeric Valeric X 10-5 Still clearer evidence should be given by solutions of the vari-ous acids at the same H ion concentration, for if the H ion is theonly toxic factor, they must all be equally toxic. Solutions weretherefore made (without buffers) of all the acids in the series atfour of the following concentrations, viz., Ph , , , , The concentrations were determined by means of indica-tors tetrabromphenolsulphonphthalein and methyl red (Clarkand Lubs, 17) in the usual way by comparison with acetic acidNa acetate standards. T
The Journal of experimental zoology . c [Valeric Valeric X 10-5 Still clearer evidence should be given by solutions of the vari-ous acids at the same H ion concentration, for if the H ion is theonly toxic factor, they must all be equally toxic. Solutions weretherefore made (without buffers) of all the acids in the series atfour of the following concentrations, viz., Ph , , , , The concentrations were determined by means of indica-tors tetrabromphenolsulphonphthalein and methyl red (Clarkand Lubs, 17) in the usual way by comparison with acetic acidNa acetate standards. The method is not perfectly exact, butupon determining the Ph of a series of equinormal acids (,, N) both colorimetrically and by calculation fromthe dissociation constants the indicators proved to be accurate towithin about Ph. The results obtained by this method are indicated in table 3and graph 4. It will be seen at a glance that the toxicity ofdifferent acids of the same Ph is by no means identical. This 458. Graph 4, E, F Toxicity of acids of equal Ph at 20°C. (Euplote^ above,Paramoecium below. Time given in minutes.) TOXICITY OF ACIDS TO CILIATE INFUSORIA 459 TABLE 3Toxicity of solutions of equal Ph at 20°C. Time in minutes ^ o 0 E I•e, 2 so 2o < 0. 3t 4 2^ 6 5 5 2 <2 <2 <^ <l 13 11 12 11 15 10 7 7 6 6 n 6 9 Paramoecium • 21 35 35 23 23 16 lU 10 11 11 11 13 10 30 100 105 60 55 20 17 16 20 20 35 30 23 25 23 35 35 30 4 5 3 3 3 2h <1 <1^ <i <1 15 20 23 13 20 10 6 7 6 6 81 6^ 17 Stylonichia < 35 48 80 25 27 30 13 14 15 11 11 15 10 75 75 50 30 28 30 23 [ 30 11 17 10 11 12 3^ H u <1 <1 Euplotes 40 60 35 35 40 42 20 19 15 15 11 10 35 60 100 60 60 70 55 55 45 33 33 40 30 100 97 55 55 [ 15 15 15 15 20 5 <3 <2 <1 <1 Vorticella { 55 75 90 90 90 55 15 15 25 25 16 16 20 1 70 80 35 40 75 33 40 30 confirms the idea suggested abo
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectzoology, bookyear1919
