PHYSICO-CHEMICAL BASIS OF TRANSMISSION 385 



protoplasmic element transmission is effected by the 

 electric current flowing between the two adjacent areas 

 of different potential. In the fuse a temperature gradient 

 exists between the burning area and the region adjoining, 

 and the reaction begins wherever the temperature reaches 

 the ignition point. The rate of transmission in such a 

 case depends on the maximal distance (from the boundary 

 of the burning area) at which this critical temperature is 

 reached and on the rate at which heat is locally developed; 

 i.e., V = Ksr where V is the speed of transmission, s 

 the maximal distance, and r the rate at which temperature 

 rises in the ignited area.^ Similarly in the nerve axone 

 (or other protoplasmic element) the velocity of transmis- 

 sion will be a direct function (i) of the maximal distance, 

 ^ (from the active area) at which the current of the 

 local bioelectric circuit is effective as stimulus, and (2) 

 of the rate, r, at which the current develops; again 

 V = Ksr. Instead of the rate of development, r, we 

 may consider its reciprocal, the time, /, required for the 

 current at the secondarily stimulated point at distance, 

 s, to attain a stimulating value; the shorter this time 

 the more rapid the transmission, i.e., V = Ks/t.^ 



This equation also applies to the transmission in the 

 passive iron model. Between the activated and the 

 inactive areas of an iron wire immersed in dilute nitric 



^ K represents constant limiting factors, such as the rate at which 

 heat is conducted or radiated from the burning region. 



The distribution of temperature in the gradient on either side of a 

 heated area in a wire (or similar heat-conductor) is in fact subject to 

 the same quantitative law as the distribution of potential in a locally 

 polarized core-conductor, as Cremer has pointed out (op. cit., pp. 906 ff.). 



2 For a fuller discussion cf. my article in American Journal of Phys- 

 iology, XXXIV (1914), 414; cf. pp. 436 ff.; also ihid., XXXVII (1915), 

 362 ff. Cremer has recently derived a more detailed formula for the 



