ABNOKMAL IRRITABILITY PRODUCED BY SALTS 699 



the solution. A number of experiments excluded the assump- 

 tion that the contraction or tetanus of the muscle which 

 occurs when it leaves the sodium-citrate solution is due to a 

 break shock. I connected the two opposite ends of the 

 muscle by means of a thick copper wire. In this case the 

 muscle contracted just as powerfully as before when taken 

 out of the sodium-citrate solution, although no break shock 

 of any strength was possible. Another still -more decisive 

 fact was found. After the muscle had been treated for some 

 time with a sodium-citrate solution the break contraction 

 could be produced by dipping the muscle for a short time, 

 e. g., thirty seconds, into a ^ or ^ solution of cane-sugar. 

 As soon as the muscle was brought into contact with air,, 

 contractions occurred. The same was true for glycerin solu- 

 tions. Both the sugar and the glycerin solution are non- 

 conductors. The possibility of a mechanical stimulation as 

 the cause of the contact-reaction was next to be considered. 

 As long as the muscle is in the solution each of its elements 

 is under the hydrostatic pressure of the column of liquid 

 above it. If we expose the muscle to the air this pressure 

 ceases. This might suggest the idea that a decrease of the 

 hydrostatic pressure upon the muscle causes its contraction. 

 The dipping of the muscle into the solution causes a relaxa- 

 tion of the concentrated muscle, and the inference should be 

 drawn that an increase of the hydrostatic pressure causes 

 relaxation. The following experiments prove the erroneous- 

 ness of this view. The bottom of the dish was filled with 

 a liquid of much higher specific gravity than the sodium- 

 citrate solution, e. </., with chloroform, 2n cane-sugar solution, 

 or metallic mercury, and the sodium-citrate solution was put 

 carefully above the sugar solution or chloroform. The 

 muscle was then brought from the sodium-citrate solution 

 into the sugar solution by raising the dish D (Fig. 162). In 

 this case I noticed regularly one or more powerful contrac- 



