1902.] 



Observations on "Flicker" in Binocular Vision. 



71 



14. The adult colour-pattern of Hippolyte cranchii is constant, but 

 develops indirectly. The adolescent possesses a special colour-patter] i 

 developed in large measure in relation with the primary system of 

 the zoea. Both persist though concealed by the independently de- 

 veloped adult pattern. 



15. In Hippolyte varians, several adult colour-patterns occur. They 

 develop indirectly. The primary system is the same in all. 



In the adolescent, three distinct colour-patterns arise : — " barred/' 

 ""liner," and "monochrome." 



These may persist, becoming barred, liner, or monochrome adults. 



Or either " barred " or " liner " may, by developing superficial or 

 deep chromatophores, become a monochrome. 



Or, by localised superficial developments either "barred " or "liner" 

 may give rise to a " blotched " adult colour-form, under which the 

 adolescent pattern is hidden. 



The primary system is inherited : the adolescent colour-patterns are 

 possibly inherited ; but inheritance is immaterial since the final goal is 

 reached by any adolescent road ; that is, the adult colour-pattern of 

 Hippolyte varians, is the result of environment. 



"Observations on 'Flicker' in Binocular Vision." By C. S. 

 Sherrington, M.A., M.D., RES. (Thompson- Yates Labo- 

 ratory of Physiology, University College, Liverpool). Re- 

 ceived July 30, 1902. 



The connection between the physiological state and reactions of the 

 two retinae right and left is close in many respects ; this is true 

 particularly and peculiarly for their areas that are conjugate in 

 "binocular vision, that is, which receive corresponding images of 

 •objects perceived in the binocular field. The observations at basis of 

 the following communication attempt to obtain further information 

 regarding; the nature of the tie between these retinal so-called " identical 

 spots." A practical aim was to measure by the " flicker " method of 

 photometry any difference of ph} T siological luminosity existent between 

 binocular and uniocular vision of a given illuminated object. 



An object intermittently illuminated gives, if the frequency of 

 intermission be sufficient, a perfectly steady sensation. The succes- 

 sive retino-cerebral reactions fuze into a continuous one as judged of 

 by sensation. If the rapidity of intermission be less than the requisite, 

 the sensation oscillates through lighter and darker phases. The transi- 

 tion from the oscillating to the steady sensation and vice versa is 

 sufficiently abrupt to form a transition point capable of fairly definite 



