PHYSICO-CHEJMICAL BASIS OF TR WSAU^ION 391 



would have a correspond in.t; ciTcct upon ihc speed ui 

 protoplasmic transmission. A lowering of the conduc- 

 tivity of the local bioelectric circuit should involve a 

 corresponding decrease in this velocity, since the n: d 



distance, s, at which the local current still has stim . g 

 intensity, would l^e i)roj)ortionately decreased by any 

 increase of electrical resistance. This critical distance 

 should, other conditions bein^ equal, be projM)rlional 

 to the conductivity of the circuit. Mayor's exiK'rimcnls 

 on the rate of transmission in the nerve net of the 

 medusa Cassiopea in dilute sea water show in fact that 

 within a considerable range of dilutions (down to 50 

 volumes per cent sea water) a close proportionality 

 exists between the salt-content of the medium and the 

 transmission rate.' This result indicates a direct 

 correlation of this rate with the electrical conductivity 

 of the medium. The recent investigation of Pond' on 

 the speed of the contraction-wave in various forms of 

 muscle (cardiac and voluntary of frog and heart of 

 Limiih(s), using mixtures of balanced Sidt solution and 

 isotonic sugar solution, has shown that in these tiivsues 

 also the speed of transnu'ssion runs closely parallel 

 wdth the electrical conductivity of the medium. The 

 transfer of a muscle from a medium of low to one ^^ 

 high conductivity is followed by a corresponding incri .i^ 

 in the speed of the contraction-wave, and vice vt 

 Mayor's and Pond's observations are dithcult to < a 



except on the assumption that electric currents tra^ 

 the cell-media are a chief factor determining thr mtr nt 



' A. G. Mayor, AmcrUan Journal oj V gy, XI-Il 



andXLIV, 591. 



' S. E. Pond, Jour. Gen. Physiol., Ill (192 1) S07. 



