[54]. I use this term physical in the sense in which it is used in the physical sciences without reference to any metaphysical concept or the ultimate nature of matter or of a physical process.
[55]. The psyche would have to be one which would be capable of becoming differentiated at one and the same moment into two independent consciousnesses—the personal and the secondary; a soul split into two, so to speak. The desire to explain a secondary consciousness by this doctrine has probably given rise to the popular notion of two souls in a single body!
[56]. If the theory of the unconscious presented in these lectures be firmly established this doctrine will have to be modified to this extent, that, while all mental processes are accompanied by brain processes, brain processes that ordinarily have conscious equivalents can within certain limits occur without them and exhibit all the characteristics of intelligence—unconscious cerebration. Indeed, it becomes probable that every mental process is a part of a larger mechanism in which unconscious brain processes not correlated with the specifically conscious processes are integral factors.
[57]. Dr. S. J. Meltzer has pointed out in a very suggestive article (Journal American Medical Association, Vol. IV, No. 12) that the anaphylactic attack resembles that of bronchial asthma in man, and argues that this latter disease may be the same phenomenon.
[58]. T. Brailsford Robertson: Sur la Dynamique chimique du système nerveux central, Archiv. de Physiol. v. 6, 1908, p. 388. Ueber die Wirkung von Säuren auf das Athmungs Zentrum, Arch. f. die Gesammte Physiologie, Bd. 145, Hft. 5 u. 6, 1912.
[59]. Stéphane Leduc: The Mechanism of Life.
[60]. Further studies in the chemical dynamics of the central nervous system, Folio Neuro-Biologica, Bd. VI, Nos. 7 and 8, 1912.
[61]. Eugenio Rignano: Upon the Inheritance of Acquired Characters. Trans. by Basil C. H. Harvey, Chicago. Open Court Publishing Co., 1911.
[62]. Prince: The Nature of Mind and Human Automatism, 1885: Hughlings-Jackson on the Connection between the Mind and Brain, Brain, p. 250, 1891; The Identification of Mind and Matter, Philosoph. Rev., July, 1904.