Anesthesia may be defined as a temporary inhibition of some physio logical activity and includes a wide range of processes such as cell division, responses to stimuli of various kinds, light-production, etc. Its chief characteristic is that the condition is reversible—that is, that normal processes are resumed on removal of the anesthetic. The anesthesia may be caused by various means—the constant electric current, change of temperature, and many chemical substances. Among the latter are the salts of Mg, Ca, and other metals, as well as the more common lipoid-soluble anesthetics—chloroform, ether, alcohol, etc. This study deals with the anesthesia of light-production in Noctiluca by means of the lipoid-soluble anesthetics.
The only previous work showing the definite anesthesia of light production in animals is that of E. N. Harvey (1915) on luminous bac teria; he found that the light could be inhibited completely by various alcohols and returned on dilution with sea-water.
Of the various theories of anesthesia, that of Overton (1901) and Meyer (1899) has received widest acceptance. According to this theory, anesthesia is due to lipoid solubility, the anesthetic dissolving in the lipoids of the cell. It has been shown by Overton that there is a direct ratio between the narcotizing power of anesthetics and their lipoid solubility—that is, the more soluble the narcotic in fat, the more narcotic power it has and the smaller the amount necessary for anes thetizing. Just how the solution of the anesthetic in lipoids should change the irritability is not explained by the theory, nor does it take into account other anesthetics which are not lipoid soluble—e. g., neutral salts. No distinction is made between the action of anesthetics in the membrane and in the cell interior. Traube (1913 and 1915) considers anesthesia as due to adsorption of the narcotic by surfaces in the cell, especially colloidal particles, due to the lowering of the sur face tension of water. This causes a decrease in catalytic activity of the surface layer, leading to a decrease in the chemical activity of the cell, especially of oxidations. It has been shown that many substances with the same surface tension have the same physiological action, although this is not always true. The fact that dried micro-organisms free of lipoids can be anesthetized supports this theory rather than the lipoid theory (Warburg and Wiese', 1912). On the other hand, the effect
of temperature on anesthesia corresponds more closely with the effect on lipoid solubility than on adsorption of the anesthetic (Meyer, 1901).
That the narcotic acts by interfering with oxidation is held by others besides Traube. Verworn (1913) considers narcosis as an asphyxia tion, since narcotized cells behave similarly to those deprived of oxygen. Mathews (1914) explains the relation of oxidation and anesthesia by assuming that protoplasm contains an unstable compound with oxygen, which breaks down on stimulation, and the anesthetic forms a stable compound with oxygen and thus prevents its liberation on stimulation. According to Mansfeld (1909), the anesthetic prevents the oxygen from entering the cell by decreasing the permeability of the surface for oxygen. In favor of these theories is the fact that oxygen consump tion by certain cells and in certain oxidations has been shown to be decreased by anesthetics (Warburg, 1911). However, in these cases the concentration necessary to decrease oxidations is much greater than that necessary to produce anesthesia. Moreover, the experi ments of Loeb and Wasteneys (1913) on sea-urchin eggs have shown that an anesthetic in the concentration sufficient to prevent cleavage had very little effect on oxidations. A slight decrease in temperature has a much greater effect on the rate of oxidations than an anesthetic of effective strength.
The membrane theory of Lillie (1909-1916) and Hober (1907) is also important. According to this the anesthetic affects the interior of the cell indirectly, the primary effect being upon the permeability of the cell membrane. The change in permeability is supposed to be connected with a change in the aggregation of colloidal particles, protein and lipoid. Lillie's experiments on Arenicola larva; show that the narcotic prevents an increase in permeability, or in some cases causes an actual decrease. Osterhout (1913) has shown also, in Laminaria, that anesthetics cause a decrease in permeability, as indicated by an increase in resistance to the electric current. This theory takes into consideration the non lipoid-soluble as well as the lipoid-soluble anesthetics.