EFFECT OF ANESTHETICS UPON LIVING PROTOPLASM. 309 



ether vapor tend to prevent the precipitation of a 0.4 per cent, 

 lecithin suspension by barium or calcium chloride. Moore and 

 Roaf 1 found that various anesthetics in high concentration caused 

 a precipitation of the proteins of blood serum. Koch and Mc- 

 Lean 2 maintained that anesthetics have no consistent effect on 

 the state of aggregation of lecithin suspensions. Warburg and 

 Wiesel 3 studied series of urethanes, alcohols, nitriles and lac- 

 tones. They found in every case that the higher members of the 

 series had a more pronounced precipitating action on yeast ex- 

 tracts. The precipitating power was correlated with the power 

 to check fermentation. Battelli and Stern* state that all anes- 

 thetics possess the power of precipitating nucleoproteins from 

 their watery extracts. Schryver 5 found that the time of gel 

 formation of sodium cholate was lengthened by the presence of 

 anesthetics. Thomas 6 found that anesthetics caused well-marked 

 changes in the viscosity of lecithin suspensions. Generally in 

 higher concentration an increase in viscosity occurred. 



With the exception of Koch and McLean all of the above 

 authors believe that the physical effects produced by anesthetics 

 upon colloidal solutions are of importance to the theory of anes- 

 thesia. But whereas some hold that the effect primarily concerns 

 the viscosity of the substances in the plasma membrane, others 

 apparently believe that the colloids of the cell interior are in- 

 volved. Not only is there disagreement as to where the effect is 

 produced but there is a decided difference of opinion as to what 

 sort of a change occurs. Some find that anesthetics cause a de- 

 crease in viscosity, others claim the reverse. This divergence in 

 results is in part explained by the fact that different authors have 

 used widely different concentrations of anesthetics. Moreover 

 the experiments have been performed upon various types of col- 

 loidal solutions. 



Although the results on inanimate substances are interesting, it 

 is obviously more significant to measure the viscosity of the living 



i Moore. B., and Roaf, H. E., Proc. Roy. Soc., 1906, B. LXXVIL, 86. 



- Koch, W., and McLean. F. C., Jo-urn. Pliarm. Exp. Therap., 1910, II., 249. 



s Warburg, O., and Wiesel, R., Arch. ges. Physiol, 1912, CXLIV., 465. 



* Battelli, F., and Stern. L., Biochem. Zcit., 1913, LII., 226. 



sSchryver, S. B., Proc. Roy. Soc., 1916, B. LXXXIX., 176. 



6 Thomas, A., /. Biol. Chein., 1915, XXIII., 359. 



