THE THEORY OF ANESTHESIA. 361 



and Gordon 1 found that lecithin suspensions containing ether, 

 chloroform, chloral, or amyl alcohol were less readily precipitated 

 by calcium and barium salts than the control suspensions, i. e., 

 were protected against precipitation or stabilized by the anaesthe- 

 tic; and they refer to this phenomenon as "narcotization of the 

 plasma-membrane colloid lecithin." Koch and McLean, 2 how- 

 ever, find that no such effect is general with anaesthetics; they 

 find chloral and ether indifferent, while chloroform protects 

 lecithin against precipitation by CaCl 2 ; on the other hand, 

 alcohol and paraldehyde further precipitation. These discrep- 

 ancies are probably due to differences of concentration. Recent 

 experiments of my own with a large number of anaesthetics have 

 shown that with the great majority of such compounds lecithin 

 emulsions may be protected to a greater or less degree against 

 the precipitating action of CaCl 2 and HC1; i. e., a concentration 

 of electrolyte just sufficient to cause precipitation in the absence 

 of the anaesthetic, fails to do so or does so incompletely in its 

 presence. The concentrations required to produce this stabiliza- 

 tion are however much higher than the anaesthetizing concentra- 

 tions, and the different compounds vary greatly in effectiveness. 

 The usual increase of action with increasing molecular weight 

 in members of homologous series (alcohol, esters) was seen. 

 But with certain compounds little or no protection was found, 

 while a few (ethyl and methyl alcohols, and in part isopropyl 

 alcohol, acetonitrile, and in part paraldehyde) definitely furthered 

 precipitation. The compounds which distinctly prevented pre- 

 cipitation included higher alcohols (w-propyl, w-butyl, i-amyl, 

 capryl), esters (ethyl nitrate, propionate, butyrate; methyl, 

 ethyl, and phenyl urethanes), hydrocarbons (chloroform, carbon 

 tetrachloride, nitromethane, benzol, toluol, xylol) ; ethyl ether, 

 chloral hydrate, chloretone, chloralose, acetanilide, phenyl urea. 

 In general, therefore, lipoid-solvent anaesthetics exhibit a stabiliz- 

 ing influence against precipitation by electrolytes, but this 

 influence is not always present. It may depend upon altered 

 electrical polarization of the colloidal particles, or possibly upon 

 increase of viscosity; but it is doubtful if in itself it forms a 



1 Hober and Gordon, Beitr. zur chem. Physiol. u. Pathol., 1904, Vol. 5, p. 432. 



2 Koch and McLean, Journ. of Pharm. and Exper. Therapeutics, 1910, Vol. 2, 

 p. 249. 



