MOVEMENTS IN THE VISUAL CELLS 



171 



TABLE 11 

 Measurements of the visual cells from the retinas of two Ameiurus and tico Abramis, 

 of which one of each had been kept at 5°C. and the other at 25°C. in the dark; the 

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

 radii of the eyeball 



by Dittler ('07), who used isolated retinas. In dark-adapted eyes 

 which were placed in water at a temperature of 33°C. the cone 

 myoids shortened (fig. 36), while at 3°C. or HJ°C. (fgs. 34, 35) 

 the myoids remained for the most part unchanged. These re- 

 sults are identical with those found by Fujita ('11) and myself 

 on the cones of living animals, and indicate that, unlike the pig- 

 ment cells, the movements of the cones are not dependent upon 

 nervous control. If an influence of the nervous system over 

 these elements exists in the normal animal, it is at least not mani- 

 fested as is the control over the retinal pigment, in which changes 

 at both high and low temperatures can be interpreted according 

 to the principle of specific energies. 



D. EFFECT OF ANAESTHETICS 



Various instances have been noted throughout this paper in 

 which the behavior of the retinal pigment and the visual cells, 

 when deprived of their blood supph', cast suspicion upon auto- 

 anaesthetization as being the factor causing suspension of move- 

 ment. Certain conditions discovered in the responses of melano- 

 phores in the web of the frog's foot had previously suggested 

 such a possibility; indeed, it was this difficulty which led to 

 the abandonment of the frog's melanophore as material for an 

 investigation somewhat similar to the present one. In this way 

 my interest was aroused to determine the effect of anaesthetics 

 on the movements of the retinal elements, both in normal animals 

 and through the more direct action upon excised eyes. 



