1913.] A Study on the Action of Surface Tension. 



549 



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desselben als Kaliumnatriuincobaltinitrit,' Inaugural Dissertation, Tubingen, 

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Concentration, regarded as the Basis of Adsorption, with an Application to the 

 Theory of Dyeing," ' Phil. Mag.,' 1908, (6), vol. 15, p. 499. 



7. Lewis, W. C. M., " An Experimental Investigation of Gibbs' Theory of Surface 



Concentration regarded as the Basis of Adsorption," ' Phil. Mag.,' 1909, (6)> 

 vol. 17, p. 466. 



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' Zeit. fur physik. Chein.,' 1910, vol. 70, p. 129. 



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VII. EXPLANATION OF PLATES. 



Note. — The dark shading in the drawings indicates the cobaltous sulphide reaction 

 developed from the treatment of the cobalt, sodium and potassium hexanitrite with 

 ammonium sulphide. The dark shading thus represents the distribution of potassium 

 throughout the organism. 



Plate 14. 



Fig. 1. — Mature specimen of Acineta tuberosa, treated to reveal the distribution of fat in 

 its cytoplasm. Formol, scarlet red, glycerine, x 700. 



Fig. 2. — Young adult specimen of A. luberosa, showing the channels in the cytoplasm 

 along which the axial contents of the extending tentacles flow. Formol, 

 scarlet red, glycerine, x 1200. 



Fig. 3. — Fully adult specimen of A. tuberosa, tentacles extended, treated to reveal the 

 distribution of potassium in it. Cobalt sodium hexanitrite, glycerine- 

 ammonium sulphide, x 750. 



Fig. 4. — Fully adult Acineta, with tentacles partly retracted and the potassium salt or 

 salts already to a certain extent diffused from the tentacles into the under- 

 lying cytoplasm. Cobalt sodium hexanitrite, glycerine-ammonium sulphide, 

 x 750. 



