Ikeda had reported that the interrelation between the mechanisms which are stimulated by red and green stimulus is independent when the duration of the test stimulus is short, but inhibitory when it is longer than about 50msec. To study why the interrelation is different due to the duration, the relation between the duration and the threshold was obtained in this paper. The results showed that two different mechanisms determine the threshold due to the duration for both red and green stimuli and it was concluded that inhibition occurs between the mechanisms which determine the threshold when the duration is long. Further, experiments of temporal summation showed that the response evoked by red stimulus inhibits that of green stimulus which is presented later than red stimulus by 60-100msec, and it was suggested that this fact may relate to the mechanism of inhibition.

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An application of complex analysis to polarization optics is given and it is shown that the Poincare sphere is nothing more than the Riemann sphere.
The approach of this paper is first to introduce the Poincare sphere by a stereographic projection of the plane representation of elliptically polarized light, where we use two orthogonal linear polarization as the basis. Then we choose two arbitrary orthogonal elliptically polarization as the basis to describe a general state of polarization and by using this general representation we define generalized Stokes parameters. The relationship between these plane representations is derived.
Next, generalized Malus' law describing the intensity of light after passage through an arbitrary analyser is obtained and it is represented by the generalized Stokes parameters.
Finally, complex analytical formulas of polarization calculus are given.

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An instrument for measuring the guide number of an electronic flash equipment is described. It is essentially an integrating photometer but incorporates a self drift compensation circuit and a logarithmic converter, so that the range of the instrument can be extended to from about 6 to 100 in guide number (for an ASA 100 film). The instrument is provided with a single range indicator having a linear scale in F number steps. The calibration is carried out by means of a standard electronic flash light source whose repeatability in successive flash is better than 0.015 step. Tests on two among thirty instruments which have been produced up to now proved that the accuracy and repeatability of the instrument are better than 0.1 and 0.05 steps respectively.

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