'For amoeboid theorists, the apparent mechanical capacity of nerve cells to alter their proximity to one another presented physical confirmation of the existence of psychological associations.

In a similar way, adherents of the protoplasmic conception of neuronal connection identified mental activity with the presumed properties of this vital substance. Especially prominent amongst such adherents was the renowned physiologist Ewald Hering... As Michael Foster put it for the 1902 edition of the Encyclopedia Britannica, '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.''