[turnbull] a subjective PHENOMENON OF VISION S3 



by a small window placed very obliquely (an arrangement by which 

 the image seen by the writer is very distinct.) 



133. Purkinje/ besides the phenomena already mentioned above, 

 describes another one in which he saw a different light after rapid out- 

 door walking in bright sunshine, and after entering suddenly a dark 

 room. This diffused light he compares to that given off by burning 

 spirits-of-wine, or to the light in darkness of a coating of phosphorus, 

 and he further says that close examination revealed that this glittering 

 mist consisted of innumerable extremely small, irregular light-points, 

 which move in different lines among one another and, gathering now 

 in one place and now in another, form indeterminate surfaces. 



134. I, myself, have seen a similar phenomenon when gazing in 

 a snow field, but can note no resemblance between it and the phenom- 

 enon described in the foregoing paper. However, Piirkinje goes on to 

 say that under certain conditions (one eye open gazing at a bright 

 surface, and one eye shut) he can again see the points, and they appear 

 more lively with opened than with closed eyes, which points to a sim- 

 ilarity in the two phenomena. 



135. Zehender (citation, par. 127) seems to have observed the 

 phenomena of the " bright jumping points,'' more easily and more 

 accurately than any other person laiowm to the writer. He sees them 

 by night and by day, with closed and with open eyes. He, howevei^, 

 mentions no regular oscillatory movement in connection with these 

 points and, although the phenomena observed by him and by the writer 

 seem to be very similar they cannot be considered identical unless 

 Zehender did not practise enough to count the oscillations. 



136. At the same time Zehender- mentions another phenomenon 

 which, in all the literature accessible to the writer, seems to be the 

 one most closely allied with the one observed by him, although here 

 again are many differences. The passage runs as follows (after men- 

 tion of a glittering light noticed as one symptom of a certain disease, 

 and also by certain persons in health) : — " From my own experience 

 I may mention that I can observe with myself a glittering more or less- 

 lively. Especially is this phenomenon observable by early morning,. 

 soon after awaking, and it is seen by me very often, I might almostc 

 say daily. In the first place, I see, with closed eyes and after day- 

 light obtains, an almost black visual field, in which, corresponding tO' 

 the direction of sight, there is a bright, pale violet spot with very inde-- 

 terminate toothed limits. This spot undergoes a continuous restless 



* " Beobachtungen u. Versuche," I 63. A book exceedingly rich in phen- 

 omena of this nature. 

 ' (Citation, par. 127.) 



Sec. III., 1906. 3 



