ABNORMAL IRRITABILITY PRODUCED BY SALTS 697 



It should finally be mentioned that sodium butyrate, 

 sodium succinate and sodium asparaginate did not produce 

 the contact-reaction. 



Having thus proved that sodium salts, whose anions 

 precipitate calcium give rise to contact-irritability, it was to 

 be expected that solutions of calcium salts would prevent or 

 antagonize the contact-reaction. I found that by adding a 

 small amount of CaCl 3 to a Na-citrate solution .the latter solu- 

 tion no longer produced the contact-reaction. The addition 

 of 1 c.c. of a 5n CaCl 2 solution to 100 c.c. of an effective 

 sodium-citrate solution was sufficient to cause a muscle to 

 lose its contact-irritability at once. Only after a prolonged 

 stay in pure sodium-citrate solution does the contact-irrita- 

 bility return. 



While all the facts thus seem to harmonize with the view 

 that a decrease in the amount of Ca ions in the tissues (and 

 possibly an increase in the amount of Na ions) is the essen- 

 tial condition for the production of the contact-reaction, it is 

 yet possible that the sodium salts whose anions form insoluble 

 calcium compounds may have a specific effect upon other 

 constituents of the protoplasm, e. g., proteids. 



III. ON THE NATURE OF THE APPARENT CONTACT -REACTION 



The reaction which we have provisionally called the con- 

 tact-reaction appears when a muscle, after having been sub- 

 merged in a sodium-citrate or any of the other above- 

 mentioned effective solutions, is brought into contact with air. 

 In this change from solution to air a number of conditions 

 change and it is now our task to determine which is the 

 essential one. 



As soon as the muscle is taken out of the solution and 

 brought into air, more O 2 may diffuse into and more CO 3 may 

 diffuse from the muscle. These two conditions have, how- 

 ever, nothing to do with the reaction. The experiments 



