Abstract
It is well known that the magnesium ion may serve as an anesthetic for many organisms. Magnesium salts are generally considered the best of all anesthetics for most types of marine invertebrates, and are also used to anesthetize the tissues of higher animals. Potassium likewise serves as an anesthetic, especially for certain types of muscular tissue. It is therefore evident that 2 of the commonest cations of the living substance may prevent its activity. Concerning the nature of the action of magnesium or of potassium, there is almost no information, and the usual theories of anesthesia offer little help.
Both magnesium and potassium ions act as anesthetics for the common Amoeba proteus. Of the 2, potassium has the more pronounced anesthetic action. When amoebae are placed in dilute solutions of potassium salts, the pseudopodia are retracted, the amoebae round up, and movement ceases completely. In solutions of magnesium salts, the effect is not so pronounced. When amoebae are placed in dilute solutions of magnesium chloride or magnesium sulphate (after a preliminary washing in the solution), movement apparently ceases. Actually a very slow change in form may persist, but there is nothing that even approaches in speed the normal amoeboid movement, and one must watch for minutes at a time to see any movement at all. (It should perhaps be noted that Amoeba dubia is much more resistant to the magnesium ion than Amoeba proteus.) When amoebae are removed from potassium and magnesium solutions and placed in balanced solutions, they recover their power of movement. Both potassium and magnesium are antagonized by calcium.
It can be clearly demonstrated that both potassium and magnesium ions have a very real effect on the physical properties of the protoplasm.
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