140 PHYSICAL CHEMISTRY 



"solutions" seems to be due to the fact that it is adsorbed by 

 the colloidal particles of lipoid so that the solution can hold more 

 anesthetic than the solvent (benzol, etc.) can. Thus we see that 

 adsorption is at the basis of the whole matter. 



In some cases the partition coefficient of the anesthetic between 

 cells or tissues and water has been determined. Warburg, by 

 this means, concluded that the erythrocytes consist of a larger 

 volume of watery phase than of lipoid phase. 



It has been shown by a number of investigators that alcohol, 

 ether, chloroform, chloral hydrate and acetone become more con- 

 centrated in nerve than in other tissue, this being used to explain 

 the ease with which the central nervous system may be anesthe- 

 tized. The nervous system, however, stores the anesthetic partly 

 in lipoids which are more abundant in the white matter, forming 

 the myelin sheaths of the nerves, and the nerves are no more 

 easily anesthetized than non-nervous cells (Gros). Nerve im- 

 pulses are still carried in the anesthetized body, only certain 

 nervous processes being stopped, as in sleep. This stoppage may 

 be explained by the assumption that certain synapses are affected 

 by the anesthetic. 



It is characteristic of pure anesthesia that it is a reversible 

 process, brought about only by a certain concentration of anes- 

 thetic. Many anesthetics, even in the optimum concentration, 

 have not only an anesthetic but also a toxic action, so that pro- 

 longed anesthesia is harmful. This is characteristic of all anes- 

 thetics with acid or basic properties, the alkaloids, for instance, 

 whose chemical affinity may explain their selective action on cer- 

 tain cell structures. Other anesthetics are decomposed in the 

 body into harmful substances. Esters are saponified with the 

 liberation of acids. 



But even the purest types of anesthetics are toxic if the anes- 

 thetizing dose is exceeded (provided they are sufficiently soluble 

 to exceed this dose). This toxic action is manifested by increase 

 in permeability, which is reversible only if very slight and mo- 

 mentary. The action of anesthetics in these high concentrations 

 will be considered in the chapter on antiseptics and in other 

 chapters. 



When ether is given to an animal, a stage of excitement some- 

 times precedes that of narcosis. This fact is open to various 



