CHANGE OF FORM IN MUSCLE DURING ACTIVITY 



147 



as about 1 m. per sec. (1*2 1*6 m.), but later investigations 

 found a much higher velocity. Bernstein, e.g. (3), gives a velocity 

 of 3 '2-4*4 ms., on measuring the latent period of the curve 

 of expansion in a given section of the muscle (gracilis and 

 semimembranosus group in frog) when excitation was applied 

 directly to the spot recording itself, and subsequently at as great 

 a distance from it as possible. The experiment was arranged as 

 in Fig. 68. It will be seen to consist in a modification of Aeby's 



FIG. 68. Rate of transmission of excitation in muscle. (Bernstein's method.) 



method, in which, however, it is not so much the velocity of trans- 

 mission of the contraction wave, as the underlying excitation, that 

 is measured, its value being taken as identical with the former. 



As the gracilis and semimembranosus muscles used by Aeby 

 and Bernstein are characterised by a very oblique tendinous 

 intersection, so that each muscle consists as it were of two com- 

 pletely separate portions, in which excitation remains isolated 

 under all conditions, it seemed advisable to repeat the experi- 

 ments with more suitable preparations. Hermann (4) accord- 

 ingly employed the two sartorius muscles of a curarised frog 



