194 PROTOPLASMIC ACTION AND NERVOUS ACTION 



critical narcotizing concentration increases; in the last 

 three (B) the conditions are reversed. Tadpoles com- 

 pletely anaesthetized at 30° in m/250 chloral hydrate 

 revive and become active on cooling the solution; on 

 warming they again become inactive. Such an effect 

 is difficult to explain except on the basis of the greater 

 lipoid-solubility of the anaesthetic at the higher temper- 

 ature, since adsorption is in general increased by lowering 

 the temperature. Meyer therefore concludes that the 

 anaesthetic produces its effect by dissolving in the cell- 

 lipoids. Such experiments seem to indicate clearly that 

 the solvent action of the protoplasmic lipoids is a main 

 factor in anaesthesia; and since anaesthesia has close 

 affinities with normal variations of irritabiUty, such as 

 sleep and fatigue, they also point to the conclusion that 

 under normal conditions the lipoids are important in the 

 cell largely because of their peculiar properties as solvents. 



The relation of the solvent properties of lipoids to 

 permeability has already been considered. The Upoids 

 thus represent the organic solvents of the cell, and 

 apparently the properties of the protoplasmic system 

 vary according to the nature and concentration of the 

 substances which they hold in solution. This is a 

 conclusion of much general interest, apart from its 

 special relation to anaesthesia, since variations in the 

 proportions of water-soluble to lipoid-soluble substances 

 no doubt occur constantly in living protoplasm. The 

 question of why such variations alter irritability, spon- 

 taneous activity, and metaboHsm will be considered 

 more fully later in connection with stimulation. 



In many cases it has been shown that the organic 

 anaesthetics accumulate in cells in greater concentration 



