The Action of Intermedin on Crustacean Melanophores and of the Crustacean Hormone on Elasmobranch Melanophores

ZO6LOGY: A. A. ABRAMOWITZ consistent judgments of brightness, and for them brightness turns out to increase with both the intensity and the frequency of the stimulus, accord- ing to the relationship which has with other observers been established for density.It seems to us, therefore, that brightness and density covary to such an extent that the two attributes ought, at least tentatively, to be identified.It is probable that two attributes, whose laws of dependence upon the parameters of the stimulus differ by an amount that is small with respect to the probable error of the judgments, would never come to be dis- tinguished.They would remain practically identical until the probable error of judgment could be reduced.In this sense at least we think that tonal brightness is tonal density as that attribute has been previously es- tablished.4Conclusion.-The brightness of tones and tonal complexes varies directly with the intensity and with the frequency of the stimulus, after the manner of tonal density.Tonal brightness and tonal density are thus probably to be identified.Of the two terms density is to be preferred, since it has been definitely established by quantitative measurement and is therefore less equivocal than brightness.