2i6 PROTOPLASMIC ACTION AND NERVOUS ACTION 



at the structural surfaces in protoplasm, and also dissolve, 

 in accordance with their partition- coefficients, in the 

 organic solvents of protoplasm. It is not a case of two 

 incompatible processes; both occur simultaneously, and 

 each contributes to the total effect. Possibly the 

 reversible effects characteristic of low concentrations of 

 anaesthetic substances are the expression of solution in 

 the lipoids, while with higher concentrations the specific 

 structural compounds of the protoplasm, the proteins, 

 are affected through coagulation or other changes due 

 to adsorption, and irreversible effects result. The 

 reversible effects — stimulation or sensitization in very 

 weak, inhibition or anaesthesia in stronger, solutions — 

 are the expressions, respectively, of facilitation and 

 hindrance of the normal metabolic processes underlying 

 stimulation and automatic activity; i.e., the influence 

 of the cell-structure on the metaboUc reactions is modi- 

 fied, and the whole behavior of the protoplasmic system 

 is altered correspondingly. 



If the influence of structural conditions on cell- 

 metabolism is to be included under the class of heterogene- 

 ous or contact catalysis, as many of the foregoing facts 

 indicate, it is evident that a consideration of this type 

 of catalysis and of the manner in which it is influenced 

 by substances of the foregoing kind becomes essential in 

 the further analysis of the conditions in living protoplasm. 



