444 PHYSIOLOGY CHAP. 



awareness of an object apart from one's self, it may obviously 

 present different degrees between the maximum and minimum of 

 distinctness and lucidity. The threshold of consciousness cannot 

 therefore be symbolised by a line, but is rather a zone which can 

 ideally be divided into different concentric regions like the visual 

 field. Between the conscious symbolically represented by the 

 central area of the retina where colour sensibility is complete 

 and the unconscious represented by the peripheral zone, where 

 there is total colour-blindness we can theoretically distinguish 

 i>t her, intermediate regions which express grades of transition 

 between the conscious and the unconscious, and are termed by 

 some neurologists semi-consciousness, nascent or twilight con- 

 sciousness. 



In these intermediate states the individual has a general 

 notion of psychical experience, a confused sense of objects, but is 

 incapable of projecting them into the external world, and of 

 distinguishing them clearly ; he cannot differentiate the self from 

 the not-self as in the fully conscious state. 



These phenomena of nascent or twilight consciousness occur 

 normally in the condition of drowsiness that precedes sleep, or the 

 half-waking state that precedes waking, in the presence of people 

 talking loudly. The individual who is in this drowsy state may 

 as many have noticed on themselves hear the different voices, 

 without being able to distinguish what is said. In the initial or 

 the final phase of sleep, auditory perceptions are confused and 

 indistinct, and almost reduced to the level of crude sensation. 

 Similar in kind is the phenomenon of indistinct and confused 

 vision normal to the achromatic border-zone of the visual field, as 

 described in previous chapters. Wliile there is distinct vision 

 that is, perfect perception of images in the central retinal area, in 

 the peripheral zone there is only confused vision that is, merely 

 a crude sensation of surrounding objects. 



These phenomena of semi-consciousness can frequently be 

 observed under a variety of abnormal cerebral conditions, e.y. in 

 fainting fits, in chloroform narcosis, in states of sub-coma and 

 stupor, in certain slight epileptic attacks, and so on. These are 

 psychical states in which the field of consciousness becomes so 

 indistinct that the individual is unable to perceive the object of 

 psychical experience clearly, although he is not " unconscious " in 

 the strict sense. 



A. Herzen (1879) x gives an interesting account of the mental 

 phenomena that develop in leipothymia or the last phase of 

 syncope, or rather in the subsequent return of consciousness. 



" During the syncope there is absolute psychic annihilation, 

 the absence of all consciousness ; then at the beginning of coming- 



"Trois phases successives du retour ;i la conscience apres une syncope," A. 

 Herzen, Revue Philosophique, xxi., 1886. 



