ANESTHESIA PRODUCED BY DISTILLED WATER

Cells of Nitella flexilis Ag. lose their power to respond to ordinary electrical stimulation after 2 or 3 days in distilled water. It returns after a day or so when they are replaced in their normal environment, in a suitable nutrient solution, or in a dilute solution of CaCl₂. Here anesthesia seems to be produced by removing something from the cell and this raises the question whether other cases of anesthesia may be explained in the same way. The antagonistic action of calcium, in some cases at least, appears to depend on its power to prevent substances from leaching out of the cell.     

CHEMICAL RESTORATION IN NITELLA : II. RESTORATIVE ACTION OF BLOOD

Cells of Nitella exposed to distilled water lose their ability to produce action currents and to distinguish electrically between sodium and potassium. This ability was quickly restored by exposure to blood plasma deprived of calcium. Human blood and that of the cat, calf, and sheep gave essentially the same results. The active agents appear to be organic substances.     

THE KINETICS OF PENETRATION : IX. MODELS OF MATURE CELLS

To imitate cells which have ceased to grow we have made models in which artificial sap is separated from the external solution by a non-aqueous layer (representing the protoplasm). A stream of CO₂ is bubbled through the artificial sap to imitate its production by the living cell. Potassium passes from the external solution through the non-aqueous layer into the artificial sap and there reacts with CO₂ to form KHCO₃: its rate of entrance depends on the supply of CO₂. Hence the increase of volume depends on the supply of CO₂ (as is probably true of the living cell). By regulating the supply of CO₂ and the osmotic pressure we are able to keep the volume and composition of the artificial sap approximately constant while maintaining a higher concentration of potassium than in the external solution. In these respects the model resembles certain mature cells which have ceased to grow.