MOVEMENTS IN THE VISUAL CELLS 



155 



TABLE 5 

 Measurements from retinas of four Abramis which had been kept at 25°C. in the dark; 

 the values are in micra and represent measurements taken along axes coinciding 

 with radii of the eyeball 



The effect of temperature, therefore, upon the cones of Abramis 

 is very marked, the length of the myoid at 5°C. (fig. 25) averag- 

 ing only 25 per cent of that at 25°C. (fig. 27), while in extreme 

 cases this ratio is as low as 10 per cent. If the mean limits of 

 myoid extension are averaged, values of 9, 24, and 35 micra are 

 obtained for the temperatures of 5°, 15° and 25°C. respectively. 

 These values are in the ratio of 1.0: 2.5 : 4.0, or in other words, 

 the 'coefficient of expansion' for the myoid of Abramis is 2 =*= 

 for 10°C. 



As a matter of fact, in the great majority of these temperature 

 experiments, 5°C\ represents a value too high and similarly 25°C\ 

 a value too low for the actual temperatures maintained. 3°C\ 

 and 26°C. are more nearly the actual values. If temperature 

 is plotted as abscissas and the myoid length in micra as ordinates, 

 the resulting curve (fig. A) is a straight line showing that the 

 temperature effect is uniform between these limits. 



The straight fine obtained in the plot may indicate that the 

 temperature response is the result of two or more opposed chemi- 

 cal reactions which operate in a compensatory manner. Since 

 the response of the nn-oid in elongating is directly correlated 

 with the temperature gradient, it seems feasible that the effect 

 of temperature is physical (in the sense of Herzog), and through 

 its action chemical processes in the protoplasm are uniformly 

 accelerated. If the length of the myoid is a fair index of the 

 chemical activity that causes elongation, and if the effect of 



