Cited by C.S. Sherrington, 'On Binocular Flicker and the Correlations of Activity of 'Corresponding' Retinal Points', Journal of Psychology 1 (1) (1904), pp. 26-60.
Description:

'There arises the question whether we may regard the dark field covering the area correspondent with that to which in the other retina a bright image is presented, as non-existent visually... in all the experiments in which a binocular image was compared with one assumed to be purely uniocular, great care was exercised to ensure absence of all trace of detail or contour from the homogeneous darkness present at the time over the whole of the other retina... When all detail and contour were absent from the field containing this correspondent area, when in fact that field was perfectly void of contours, and homogeneous, unchanging and borderless, it was found that it mattered little what depth of darkness it might have; it might be a shade of grey or even a fair white, without perceptibly influencing the sensual vibrations given by the flickering image before the other eye. The absolute blankness of the field seemed to unhitch the region of retina which it covered from higher cerebral connexions, at least to prevent its reactions from contributing to consciousness... Under this blankness the 'retinal-points' become unhitched from the running machinery of consciousness, if — and this is essential — the 'corresponding' retinal area be concurrently under stimulation by a defined image. McDougall's [note: 'Mind, 1902, N.S. XI. p. 316'] principle of competition for energy between associate neurones seems at work here, for with both eyes shut the dark blankness of eye-closure does become visible.' (39-40)

 

McDougall's article introduces what Sherrington calls his 'principle of competition for energy' as follows:

'The constituent neurones of the nervous system with all their branches are regarded, 'in primitivster Weise' as Münsterberg says, as a vast system of channels in all parts of which potential chemical energy is constantly being transformed, in virtue of the normal activity o fthe neurones, into a peculiar form of active energy. This energy, which in the present state of our ignorance, can be most profitably regarded as a fluid, tends always to flow, like heat, electricity or water, from places of higher to places of lower potential, following the paths of least resistance, and for convenience of description it may be called 'neurin'... neurin flows perpetually through the intricate labyrinth of paths that constitutes the central nervous system from the afferent towards the efferent neurones. But the channels along which it has to find its way are not completely or equally open; while each neurone presents throughout its length, dendrites, cell-body and axone, an open channel offering no resistance, each is separated from all others with which it is functionally connected at synapses by an intercellular substance which presents a certain resistance to the passage of neurin from one neurone to another. In the resting state, as during deep sleep, neurin flows slowly and equally through all parts, maintaining in some degree the tonus of the nervous and muscular systems, and escapes across the resistant synapses by a sort of leakage. But, when a definite supraliminal stimulus, is applied to a sense-organ, the sensory neurones affected by it produce neurin much more rapidly than it can escape by leakage across their efferent synapses, so that the potential of their charge very rapidly reaches what may be called the level of the threshold of the synapses, i.e., it reaches such a degree that a rapid discharge of neurin takes place through the intercellular substance of the synapses into efferent neurones, [note: 'It is convenient to speak of each neurone in any chain of neurones forming a conduction-path from sense-organ to muscle as afferent to its successor and ae efferent to its predecessor in the chain.'] i.e., into neurones of the second of those several layers in which the neurones leading from sensory to motor organs are arranged.' (329-330)