Migration of the Retnial Pigment 



545 



my methods. The average positions of the proximal pigment of 

 different animals formed a natural series, although the average 



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rig. 5 Fig. 6 Fig. 7 



Figs. 5 to 7 longitudinal sections of retinular and sub-retinal portion of the eye of Cambarus, magnified 

 350 diameters, showing the distribution of the retinal pigment under the following conditions: 

 Fig. 5, in dark and at 2° C. 

 Fig. 6, in dark and at 22° C. 

 Fig. 7, in dark and at 34° C. 



interval between the temperatures employed was only about 6° C. 

 At 2° C. (Fig. 5) a considerable amount of the proximal pigment 



