Specific Gravity and Luminescence in Noctiluca, etc. 249 



All of these theories fall into two groups: those which consider the 

 action of the anesthetic to be upon the cell-membrane and those which 

 consider the action to be directly upon the cell-contents. Experiments 

 on the anesthesia of light-production in Noctiluca have been carried 

 out in the attempt to find out which of these two alternatives is correct. 



Although the anesthesia of some processes has been shown to be 

 independent of the consumption of oxygen for instance, the cleavage 

 of sea-urchin eggs (Loeb and Wasteneys, 1913, and Warburg, 1910)- 

 it would seem probable that the anesthesia of light-production is depen- 

 dent on oxygen. That oxygen is necessary for light-production in 

 Noctiluca has been shown by keeping the cells in an oxygen-free atmos- 

 phere, in which case the luminescence stops, but reappears on admitting 

 oxygen. The membrane is freely permeable to oxygen at any time, since 

 those cells deprived of oxygen immediately glow on admission of oxygen. 

 It may be noted in passing that this oxidation is different from that of 

 other cells, as shown by the fact that KCN in relatively high concen- 

 trations has no effect, whereas it so quickly affects other oxidations. 



The anesthesia must in some way affect the oxidation which is con- 

 cerned in light-production. Does it do so by preventing oxygen from 

 entering the cell, or does it prevent the utilization of the oxygen 

 already present in the cell? In other words, does the anesthetic act 

 upon the membrane or directly upon the cell interior? 



In my experiments various lipoid-soluble anesthetics were tried and 

 the effect of the anesthetic has been in all cases not to prevent light- 

 production altogether, but to prevent a normal response i. e., a flash- 

 ing on stimulation. In all the effective concentrations, the animals 

 under the anesthetic produce a steady glow, so faint in some cases that 

 it is not noticeable unless the animals are present in large number. 

 When returned to sea-water, if not left too long in the solution, the 

 steady glow ceases and the normal response returns ; this is therefore a 

 reversible phenomenon and a true case of anesthesia. The best concen- 

 trations for anesthetizing, as seen by referring to table 6, were: 1/3 sat- 

 urated chloroform, where the steady glow lasted 2 hours; m/8 ether and 

 m/8 butyl alcohol, steady glow lasting 1^ hours; 1/16 saturated thymol, 

 lasting 1 hour; methyl alcohol, lasting 30 minutes, and 1/4 to 1/8 

 chloretone, lasting 15 minutes. If returned to sea-water after the 

 period of steady glow, the animals gave no response, the prolonged 

 anesthesia causing death. The tentacle motion was also stopped by 

 the anesthetic in the same concentrations as prevented the normal 

 light-response. The effect on the tentacle was, however, much slower 

 than the effect on light-production, but took place during the early 

 part of the period of constant glow. 



The question as to whether the effect of the anesthetic is upon the 

 interior of the cell or upon the cell membrane was tested by destroying 

 membranes, thus allowing oxygen to enter. A number of noctilucas were 



