[67] The scientific psychologist will perhaps read with impatience expositions with which he is so familiar; but they are, unfortunately, not superfluous for a very numerous class of even highly educated persons, who have never had instruction in the laws of the operations of the brain.
[68] Mosso’s experiments on, and observations of, the exposed surface of the brain during trepanning have quite established this fact.
[69] The experiments of Ferrier, it is true, have led him to deny that a stimulus which touches the cortex of the frontal lobes can result in movement. The case, nevertheless, is not so simple as Ferrier sees it to be. A portion of the energy which is set free by the peripheral stimulus in the cells of the cortex of the frontal lobes certainly transmutes itself into a motor impulse, even if the immediate stimulation of the anterior brain releases no muscular contractions. But this is not the place to defend this point against Ferrier.
[70] A. Herzen is the author of the hypothesis that consciousness is connected with the destruction of organic connections in the brain-cells, and the restoration of this connection with rest, sleep, and unconsciousness. All we know of the chemical composition of the secretions in sleeping and waking points to the correctness of this hypothesis.
‘One tread moves a thousand threads,
The shuttles dart to and fro,
The threads flow on invisible,
One stroke sets up a thousand ties.’
[72] Karl Abel, Ueber den Gegensinn der Urworte. Leipzig, 1884.
[73] James Sully, Illusions. London, 1881.
[74] Th. Ribot, Psychologie de l’Attention. Paris, 1889.
[75] It is possible that an active expansion of the bloodvessels does not take place, but only a contraction. It has been lately denied that there are any nerves of vascular dilatation (inter alia by Dr. Morat, La Semaine médicale, 1892, p. 112). But the effect may be the same in both cases. For through the contraction of the vessels in a single brain-circuit, the dislodged blood would be driven to other portions of the brain, and these would experience a greater access of blood, just as if their vessels were actively dilated.