ACIDS AND ALKALIES.
For ascertaining the effects of acids on the luminescence of Nodiluca, hydrochloric (a lipoid insoluble) and benzoic (a lipoid soluble) acids were used, the solutions being made up in a neutral artificial sea-water, m/2(100 NaCI+2.2 KC1-1-2 CaC12-1-10 MgC12), so as to avoid the disturbing presence of the buffer phosphates and carbonates.
Certain concentrations of these acids, n/2000 to n/4000 HC1 and n/4000 C2H2COOH, cause a bright continuous glow lasting from 20 to 60 minutes (table 4). The glow in these solutions becomes gradually 'The constant glow at the start is without doubt due to the dying condition of some of the animals.
'The normal response at the start is doubtless due to the delay in taking effect.
brighter, stays at a maximum for some time, and then becomes gradu ally fainter. In n/4000 HC1 the animals also give a normal response— that is, they flash on stimulation while they are giving a steady glow. Whether it is certain animals in the solution that give the one response at the same time that others are giving the other, or whether all of the animals give both responses, it was not possible to determine. Stronger concentrations of these acids kill the animals almost instantly, while weaker concentrations have practically no effect.
The alkalies NaOH (lipoid insoluble) and (lipoid soluble) have an effect upon luminescence similar to that of the acids, except that the constant glow is more faint and of shorter duration; n/125 to n/250 NaOH and n/250 to n/1000 (the first two solutions were made up in Mg-free sea-water, all the others in artificial sea water) cause a constant glow lasting from 30 seconds to 4 minutes, and no normal response is given (table 4). In slightly weaker solutions,
n/500 NaOH and n/2000 a normal response is given for a short period, owing doubtless to a delay in penetration, followed by a constant glow.
In one series of experiments comparison was made of the penetration time of the alkali and its effect on luminescence. The comparison was made on the same lot of animals stained with neutral red, which is not harmful to them. One set was observed in the dark for the effect on luminescence, while the other set was watched simultaneously by an assistant for color-change. In the case of NaOH the color-change from red to yellow takes place only after all light-response has stopped, whether this be a steady glow or a normal response; NaOH, therefore, does not penetrate the cell until after luminescence has ceased. On the other hand, with the color-change takes place before the effect on luminescence has stopped—that is, the alkali penetrates the cell while it is still giving a luminous response. For example, in n/500 the color-change takes place in 30 seconds, while the constant glow lasts 75 seconds. These results tally with those of E. N. Harvey (1914), who found that in certain plant and animal cells NaOH pene trates the cell only after its death, while penetrates before the death of the cell. The effect of alkalies on light-production is therefore brought in line with its effect on muscle-contraction, protoplasmic rotation, and other physiological processes.