ix PSYCHO-PHYSICAL PHENOMENA 455 



forms of life, as the germ or immediate potentiality of the 

 conscious, which develops in the higher animals and in man by a 

 process of evolution. The subconscious in plants and metazoa is 

 the same as that specific activity of living beings which Aristotle 

 and Leibniz termed entelechia. 



Admitting the credibility of this hypothesis it follows logically 

 that in the higher animals and man, with elaborate nervous 

 systems, the region of the unconscious is not confined to the 

 organs of animal life, but extends beyond it to embrace the 

 vegetative organs. 



V. The segmental theory founded by Moquin-Tandon (1827) 

 and Duget (1837), according to which animals, generally speaking, 

 result from a series of complex morphological aggregates (the 

 zoonites of invertebrates, metameres of vertebrates), each of which 

 represents in miniature the organisation of the animal to which it 

 belongs, has been much developed, and has acquired a general 

 biological importance. 



The foundations of a segmental anatomy are already laid. 

 We know that the skeletal system and muscles, the nervous 

 system, and the skin of vertebrates exhibit in early developmental 

 stages or throughout life, in certain parts or in the whole organism, 

 a more or less obvious division into segments of the same kind 

 arranged in series. This is shown by a mass of different re- 

 searches of various kinds, of which van Kynberk published a bib- 

 liography in 1908, which are the foundation-stones of a segmental 

 physiology, or the arrangement of functions according to their 

 uni- or pluri-segmental localisation. Van Eynberk has indicated 

 this in a recent memoir (1912). 



The most interesting fact from our point of view is that in 

 proportion as we ascend the zoological scale the unitary or monozoic 

 constitution gradually replaces the segmental or polyzoic, owing 

 to the increasing interpenetration and fusion of the com- 

 ponent segments. The zoonites of invertebrates, which represent 

 an almost independent individuality, become metameres in verte- 

 brates, which while they have the same biological significance 

 are closely interconnected. From Amphioxus to Man, meta- 

 merisation, which is obvious during embryonic development, 

 becomes more and more masked during development, while the 

 centralisation effected particularly by the nervous system is 

 increasingly emphasised in the higher animals. 



Man, at the summit of the scale, presents the most complicated 

 constitution, and is at the same time the most profoundly unitary 

 of all living beings : this is evident in the phenomena of the self 

 or sense of personality, which maintains a steady and apparently 

 invariable attitude in face of the incessant stream of thoughts, 

 feelings, and actions. 



Nevertheless, the self, as already pointed out, comprises only a 



