MOVEMENTS IN THE VISUAL CELLS 



175 



efficient. The experiments with chloretone and urethane also 

 prove that even though the animal as an organism dies, the 

 pigment, nevertheless, can expand independently. 



b. Visual cells 



Experiments similar to those just described were repeated 

 in order to determine the action of anaesthetics on both rod and 

 cone cells. Since the cone myoid is maximally elongated at 

 about 25°C. in the dark (figs. 25, 27), this condition was taken 

 advantage of in producing sharp contrasts between dark and 

 light phases. The cones of Abramis and Fundulus, on account 

 of their great contractility, were particularly favorable for ob- 

 servation, as were the rods of Ameiurus becau.se of their large size. 



The results of these experiments are shown in table 12. 



TABLE 12 

 A tabulation of the effects of carbon dioxide and ether upon the movements of the 

 visual cells of Ameiurus, Abramis, and Fundulus; X indicates that the movements 

 of the elements were completely arrested; conditions corrcspotidittg to the blank- 

 spaces were not investigated 



The conclusion is, therefore, that both ether and carbon diox- 

 ide anaesthetize the visual cells of normal fishes to such an extent 

 that neither light nor temperature is efTecti\e in causing positional 

 changes. 



A few experiments upon the excised eyes of Ameiurus showed 

 that both carbon dioxide and ether have the same anaesthetic 

 effect on the rods and cones as that described for normal animals. 



Whether or not autoanaesthetization prevented movements 

 of the retinal elements, as was suspected in previously described 

 experiments when the normal blood supply was interrupted, it 

 is at least demonstrable that certain anaesthetics do act in a 



