Vol. XI. July, 1906. No. 2 



BIOLOGICAL BULLETIN 



ON THE INFLUENCE OF ELECTROLYTES UPON 

 THE RATE OF RHYTHMIC MUSCULAR CON- 

 TRACTIONS (PRELIMINARY 

 COMMUNICATION). 



T. BRAILSFORD ROBERTSON. 



[From the Rudolph Spree kles Physiological Laboratory of the 

 University of California.] 



I. In a previous paper J I have suggested that the rate of beat 

 of a rhythmically contracting tissue, such as the heart, may be 

 connected with the velocities of the ions in the tissue-fluids, or 

 in the medium in which the heart is suspended, by the following 



formula : 



u 



t=a 



, 



v(u + v) 



where / is the interval between the beginning of one beat and the 

 beginning of the next, u is the average velocity of the kations 

 in the medium, v that of the anions in the medium and a and b 

 are constants for any given heart. 



2. The assumptions involved in the deduction of this formula 

 are : (i) That the ions diffuse into the tissue in numbers propor- 

 tional to their migration-velocities in water ; (2) that they give 

 rise to a reversible chemical change in the tissue, a change con- 

 sisting in the displacement of ions already present in the tissue in 

 ion-proteid compounds by those which have newly entered, and 

 that this reaction obeys Guldberg and Waage's mass-law and (3) 

 that the ions thus displaced in each successive segment of tissue 

 give rise to the contraction. 



1 Pfliiger's Arch. f. d. ges. PhysioL, Bd. HO, p. 610. 



53 



