MOVEMENTS IN THE VISUAL CELLS 



159 



TABLE 9 

 Measurements from the retinas of four Cara^sius, two of which had been kept atS°C., 

 and two at 25°C. in the dark; the values are in micra and represent measurements 

 taken along axes coinciding with radii of the eyeball 



2. Frog. (1) Rana pipiens (adult). Gradenigro ('85), Ange- 

 lucci ('90), Herzog ('05) and Fujita ('11) have all stated that at 

 a temperature of 30°C. or more, the cones of the frog shorten 

 until they assume the position characteristic of light. Thus, 

 Herzog (p. 419) says: "Aufenthalt im Briitschrank 1/2 Stunde 

 lang, Temperatur von 21° bis 30° C. ansteigend: . . . die- 

 selbe zeigt auch, dass die Zapfen maximal contrahiert sind. Die 

 Lange der Zapfen betriigt mit ganz vereinzelten Ausnahmen 

 0.0091 mm. (v. d. Lim. (^xtern. — Oelkugel excl.)." 



The action of low temperature was first tried by Herzog ('05), 

 who makes the following statement (p. 424). concerning the re- 

 sult of two hom's" cooling to (f(\ in the dark: ''Dagegen sind 

 die Zapfen bereits nahezu hochstgradig verkiirzt. Ihre Lange 

 betragt fast durchweg 0.0078 bis 0.0091 mm." 



Fujita experimented upon six frogs, which were kept at 

 a low temperature in an 'P^isgefass' for periods of 30 minutes 

 to 6 hours, after which the decapitated heads were fixed in 

 ice-cold fluid. His conclusion (p. 170) is diametrically opposed 

 to that of Herzog. "Das Resultat war in alien Fallen das gleiche : 

 ich konnte keine Hellstellung konstatieren. Die Zapfen waren 

 nicht kontrahiert " 



Measurements showing the elongation of the cone myoid at 

 intermediate temperatures (14° to 19°C.) are not given by Herzog, 

 who, however, states (p. 418) concerning retinas that had been 

 raised in the course of 15 minutes from 18° to 24°C.: ''Ein 

 wesentlicher Einfluss is nicht zu erkennen Die 



