138 Papers from the Marine Biological Laboratory at Tortugas, 



its value in sea-water), while in CaCl2 or lanthanum chloride the con- 

 ductivity decreased. Under the conditions of the experiment, increase 

 or decrease in conductivity denotes a corresponding increase or decrease 

 in permeability. The changes in permeability induced by NaCl, CaClg, or 

 LaCls are readily reversible within certain limits on returning the tissue to 

 sea-water. 



My own experiments, cited above, indicate that NaOH may enter many 

 kinds of eggs much more readily when dissolved in 0.6 m. NaCl than in 

 0.625 m. Mg-free sea-water. The pure NaCl evidently decreases the 

 resistance^" of the egg-surface for NaOH. 



The surface of Elodea and Spirogyra cells is likewise affected by minute 

 traces of substances in solution. For instance, N/40 NaOH dissolved in 

 tap-water entered Spirogyra in about 40 minutes; dissolved in double dis- 

 tilled water, condensed in soft glass, ^Mn about 10 minutes; and dissolved in 

 N/io NaCl, instantly. Again the resistance of the surface is greatest in the 

 medium most nearly normal. Addition of CaCla to the NaCl prevents so 

 rapid penetration of NaOH.^ 



Anaesthetics give similar results with Elodea cells. Chloroform added 

 to N/40 NaOH to 1/6 saturation increases the penetration rate from 90 

 to 13 minutes. The protoplasmic rotation characteristic of the Elodea cells 

 ceases in 1/6 saturated chloroform, but the effects of the chloroform are 

 completely reversible, for, on removing the leaves again to pure water, 

 rotation promptly begins. Alcohol and ether act in a similar manner. 



That chloroform increases permeability in 1/6 saturated solution may 

 be verified by the plasmolytic method. Such "reversibly" chloroformed 

 cells are plasmolyzed by urea much less readily than normal cells, a result 

 indicating that the urea enters more rapidly.^' 



On the other hand, Lillie^* cites evidence to show that very small con- 

 centrations of anaesthetics decrease permeability. 



PERMEABILITY AND FUNCTIONAL ACTIVITY. 



Lillie^^ has advanced evidence showing that stimulation of muscle-tissue 

 is accompanied by an increase in permeability of the tissue. Those sodium 

 salts which are most effective in stimulation are most effective in causing the 

 loss of pigment from the tissues of Arenicola larvae. Loss of pigment indi- 

 cates increased permeability to pigment. The same is true as regards 

 artificial parthenogenesis. These salts most effective in stimulating devel- 

 opment cause most rapid loss of pigment from the eggs (Arbacia) ;^^ they are 

 also most toxic; in them death of the egg ensues most rapidly. It has long 

 been known that the condition of death is one characterized by marked 

 increase in permeability. The change on stimulation is in the direction of 

 that accompanying death. 



"The word resistance is used instead of permeability to indicate that the cell is normally impermeable to 



NaOH which only enters after affecting the cell-surface. 

 " Such water is perfectly harmless for both Spirogyra and Paramecium, a good test of the purity of a water. 

 " Harvey, E. N. Loc. cit., p. 540. 

 " Harvey, E. N. Loc. cit., p. S39. 



"Lillie, R. S. Amer. Jour. Physiol., vol. 29, p. 372, 1912; vol. 30, p. i, 1912. 

 •* Lillie, R. S. Amer. Jour. Physiol., vol. 24, p. 14. 1909. 

 "Lillie, R. S. Amer. Jour. Physiol., vol. 26, p. 106. 1910. 



