PLATE 4 



EXPLANATION OF FIGURES 



These photographs, taken with a Leitz -^2 homogeneous immersion objective, 

 are at a magnification of 715 diameters and show the responses of the myoids of 

 the cone cells of fishes when under the influence of temperature. 



25 Abramis, 3°C. in the dark. 



26 Abramis, 15°C. in the dark. 



27 Abramis, 27°C. in the dark. 



28 Fundulus, 3°C. in the dark. 



29 Fundulus, 27°C. in the dark. 



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