Action spectra derived from dose-response curves measured for various processes associated with chloroplast development in Euglena gracilis var. bacillaris are presented. The action spectrum for chlorophyll synthesis during the first 36 hours of continuous illumination of dark-grown resting cells resembles the absorption spectrum of protochlorophyll(ide). The action spectrum for the ...

Experimental in vitro studies have been made on the intracellular electrical activity and the extracellular wave movements of ciliary cells in rabbit trachea. The following results were obtained: 1. Surface light reflections from the mucous layer and from the ends of moving cilia showed about the same frequency and amplitude ...

The sources of optical retardation changes and light scattering changes occurring during the action potential propagation of lobster giant axons have been investigated. A technique has been developed for resolving the total transmitted-light intensity change into a retardation change component, dI-r, and a forward direction light scattering change, dI-s. Trypsin, ...

The action spectrum for the initiation of fruiting (primordium formation) in Favolus arcularius was determined on the equal response basis. The detectable effect of light was observed in the region between 350 to 560 nanometers, showing six distinct peaks at 374, 398, 424, 446, 480, and 514 nanometers. The half ...

A small volume of an erythrocyte suspension was subjected to the action of a manipulated gas bubble set into stable oscillation at 20 kilohertz. Release of hemoglobin occurred when the oscillation amplitude exceeded a critical threshold. Hydrodynamic stresses resulting from acoustically induced small-scale eddying motion near the bubble may be ...

The action spectra for phycocyanin production by the cyanophyte Fremyella diplosiphon shows maxima at 463 and 641 nm. The action spectrum for phycoerythrin production includes maxima at 387 and 550 nm. The maxima are based on a relative response rate well within the linear ascending portion of the dose response ...

Light is required for the herbicide activity of diphenyl ether herbicides. An action spectrum of acifluorfen-methyl activity with Chlamydomonas eugametos (Moewus) determined that cell death occurred at two peaks of light; 450 and 670 nanometers. These data indicate both chlorophyll and carotenoids, but not riboflavin, are involved in herbicide toxicity.

Differentiation of Chlamydomonas reinhardtii vegetative cells to gametes requires two environmental signals: nitrogen starvation and light. Vegetative cells incubated without nitrogen differentiate into pregametes. Pregametes can be converted into sexually mature gametes by irradiation with light. The action spectrum for the light-dependent step in gamete formation showed two maxima at ...

Action spectra were measured for suppression of germination of Poa pratensis L. and Amaranthus arenicola I. M. Johnston seed under prolonged or continuous irradiation. The action maxima for both types of seeds are near 720 nm. The maxima are unchanged in position or magnitude in the presence of radiation in ...

An action spectrum of the 520 mμ difference band in Chlorella is determined using dim illumination. Pigment (or pigments) absorbing most strongly at and above 680 mμ, probably the so-called “long-wave forms” of chlorophyll a appear to be the primary sensitizer of the 520 mμ effect.

The influence of light environment on the organic constitution of normal rabbits was studied by comparing the weights of organs of animals that had been living under cerrtain conditions for long periods of time. It was found that the light environment produced an effect on the physical constitution of the ...

The action spectrum for breaking diapause in the oak silkworm, Antheraea pernyi Guer., and the codling moth, Laspeyresia pomonella (L.), was determined from 400 to 700 nm with a wedge-interference spectrograph. Insects were exposed to ten hours of white light, followed by six hours of spectral light each day for ...

A new kind of statistical display, the joint peri-stimulus-time scatter diagram, facilitates the analysis and interpretation of two or more simultaneously recorded trains of action potentials. The display is a generalization of the cross correlation and the peri-stimulus-time histogram, and it reflects specific underlying neuronal interactions. The technique yields quantitative ...

A circadian rhythm of egg hatching in the moth Pectinophora gossypiella can be initiated with a brief light pulse. The action spectrum for this effect has a peak in the blue and near ultraviolet region of the spectrum with a sharp cutoff above 500 nanometers and a more gradual cutoff ...

Action spectra were measured for suppression of germination of Poa pratensis L. and Amaranthus arenicola I. M. Johnston seed under prolonged or continuous irradiation. The action maxima for both types of seeds are near 720 nm. The maxima are unchanged in position or magnitude in the presence of radiation in ...

When spines on the scape and pedicel of two species of saturnid moths were irradiated with visible coherent (6328 A) and incoherent radiation, the sensors responded to the light by sending a biphasic nerve impulse down the entire length of the central antennal nerve. The biphasic action potential apparently gates ...

Of the three hypotheses on the mechanism of the action of phytochrome (by means of growth stimulants, by means of a common link in the metabolism, and by a system of regulation) the one which is apparently closest to the truth is the third one which speaks of the action ...

The oxygen consumption of a starved chlorophyll-free, yellow mutant of Chlorella vulgaris is enhanced by very small amounts of blue light (lambda 450 mmu); a saturation level is reached at about 500 ergs cm(-2) sec(-1). At that intensity the respiration is about 3 times greater than in the dark. An ...

1. The problem of colour reception is that we do not know the action spectra of the visual pigments involved, the nature of the signals generated nor the interaction between these signals. We only know the incident light and the electric results of interaction.2. In Part 1 we show that ...

The effect of relative humidity (RH) and inositol on the lethal action of artifical sunlight has been studied. The letgality of these radiations isshown to be strongly dependent on RH provided the intensity of the light is not /oo great. A critical region between 55 and 65% RH exists in ...

Observation of the action potential and contraction of the leaf of Dionaea muscipula Ellis revealed several interesting phenomena. Two successive stimuli are generally necessary to cause contraction. The first and ineffective stimulus is associated with slow depolarization. The second stimulus has much more rapid depolarization and initiates contraction.

The luminescence of the marine dinoflagellate Gonyaulax polyedra shows an endogenous diurnal rhythm. The effect of light during the phase of low luminescence capacity may be observed as an enhancement of luminescence during the subsequent bright phase. During the bright phase, however, illumination diminishes the capacity for luminescence. The action ...

The simple conclusion of former investigators that the shorter the wave length of ultra violet light the greater the bactericidal action is in error. A study with measured monochromatic energy reveals a characteristic curve of bactericidal effectiveness with a striking maximum between 260 and 270 m.micro. The reciprocal of this ...

1. Wide differences in the intensity of incident ultra violet energy are not accurately compensated by corresponding changes in the exposure time, so that the Bunsen-Roscoe reciprocity law does not hold, strictly, especially for bactericidal action on young, metabolically and genetically active bacteria. In the present series of experiments, however, ...

In this first paper of a series on the bactericidal action of ultra violet light the methods of isolating and measuring monochromatic radiations, of preparing and exposing the bacteria, and of estimating the effects of exposure, are given in detail. At all the different wave lengths studied the reactions of ...

The influence of light environment on the organic constitution of normal rabbits was studied by comparing the weights of organs of animals that had been living under cerrtain conditions for long periods of time. It was found that the light environment produced an effect on the physical constitution of the ...

Our only direct intimation of the existence of space is the sensation of vertigo, when through our cortical centres we become conscious of the fact that we are surrounded by a "blank" space in which motion is apparent, i.e., the relative condition of our body to the things around us ...