Quoted by T. Quick, 'Disciplining Physiological Psychology: Cinematographs as Epistemic Devices, 1897-1922', Science in Context 30 (4), pp. 423-474.
Description:

'adherents of the protoplasmic conception of neuronal connection identified mental activity with the presumed properties of this vital substance. Especially prominent amongst these was the renowned physiologist Ewald Hering. Calling for physiologists to 'cease considering physiology merely as a sort of applied physics and chemistry,' Hering argued that the causes of nervous action were to be found in two independent and contradictory tendencies of protoplasmic matter. [note: 'E. Hering, 'On the Theory of Nerve Activity', The Monist 10 (2) (1900), pp. 167-187, on p. 169.'] On the one hand, a tendency towards 'assimilation' could be perceived within living substance. This was balanced by an equal and opposite tendency, that towards 'dissimilation'. Where assimilation predominated, organic matter increased in activity. Where dissimilation predominated, activity decreased. There were thus 'two closely interwoven processes, which constitute the metabolism (unknown to us in its intrinsic nature) of the living substance'. [note: 'E. Hering (trans. F.A. Welby), 'Theory of the Functions of Living Matter', Brain 20 (1-2) (1897), pp. 232-258, on pp. 232-233.']  The variable energetic states of protoplasm expressed itself in the nervous system as the throwing-out of countless connections between cellular bodies: 'a nerve-trunk is... a bundle of living arms which the elementary organisms of the nervous system send forth for the purpose of entering into functional connexion with one another, or of permitting the phenomena of the outside world to act upon them, or of exercising control over other organs'. [note: 'Hering, 'On the Theory of Nerve Activity', pp. 177-178.']  As Foster put it for the 1902 edition of the Encyclopedia Brittannica, 'in Hering's conception the mere condition of the protoplasm, whether it is largely built up or largely broken down, produces effects which result in a particular state of consciousness.' [note: 'M. Foster, 'Physiology', in Encyclopedia Britannica, (10th ed.) Vol. XIX. (New York: Werner, 1902), pp. 8-23, on p. 22.']  Sensation was not so much the consequence of impressions on sensory organs that were then conveyed to the mind via the nerves, as the establishment of sympathetic rhythms between the various realms of existence. Thus in the case of visual sensations, Hering argued that protoplasm vibrated according to the frequency of light-waves connecting with the retina. [note: 'Hering, 'On the Theory of Nerve Activity', pp. 183, 186.']  Brain recounts how at the Paris Societé de Biologie, Binet and others developed similar explanatory schema to account variously for hypnotic and hysteric states, sleep, aesthetic experience, and even paranormal phenomena. [note: 'R.M. Brain, 'Materialising the Medium: Ectoplasm and the Quest for Supra-Normal Biology in Fin-de-Siècle Science and Art', in A. Enns and S. Trower (eds.), Vibratory Modernism (Basingstoke: Palgrave Macmillan, 2013), pp. 115-144, on pp. 125-127.'] Protoplasm spread both inwards and outwards from the vital mind, bringing mental life into vibratory harmony with that with which it connected.'

 

Relevant passage from Hering:

 

'To assimilate and dissimilate is a fundamental property of living matter, engrained deeply in its nature, and these functions continue - provided the essential conditions of life are present - without assistance from external stimuli; we are thus free to regard what are here termed vital conditions as being in part "internal" stimuli.

In so far as living matter is wholly unaffected by adventitious, external stimuli, its assimilation (A), and dissimilation (D), may be denoted autonomous.

So long as the autonomous D and A are equal, the state of the living matter cannot alter; qualitatively and quantitatively it remains the same. Such a state of perfect equilibrium between the autonomous D and A may be designated autonomous equilibrium.

This state of living matter is altered when any stimulus excites it to active dissimilation, no longer balanced by equal assimilation. Such dissimilation is no longer exclusively autonomous; it is reinforced by external factors, and must be denoted allonomous, in contradistinction from the pure autonomous process. The increased formation of D-products, and corresponding loss of elements that were formerly an integral part of the living matter, and included in its chemical structure, produces internal alteration in the substance, in proportion with the intensity and duration of the stimulus. Hence at the close of excitation the living matter is quantitatively and qualitatively (infra) altered.' (232-233)