62 



it considerable. The contraction of muscle exposed to high pres- 

 sures has been known for a long time as ""Ebbecke's phenomenon." 



Bulky ions, such as I~, SCN", and NOs", which do not fit into 

 the water lattices, should impede the formation of these lattices 

 and thus counteract relaxation, lengthening the "active state" of 

 muscle, and thus increase twitch tension. That this is the case has 

 been sho'^n by Chao and the later analyses of his observations by 

 Kahn and Sandow, Hill and Macpherson, and Ritchie. The action 

 of these ions was found to depend on their position in the 

 "Hofmeister series," that is on their atomic radius. Since these 

 ions are "quenchers," they may have acted also by interfering with 

 E*. 



Needless to say that the function of muscle is not merely to 

 contract, but to contract when contraction is needed, and do so at 

 milliseconds notice, and relax immediately afterward when the 

 job is done. Accordingly, we find in muscle at the side of myosin 

 a triggering mechanism in which actin plays a prominent role. 

 According to the experience of my laboratory, resting muscle con- 

 tains no actomyosin, but contains actin and myosin side by side, 

 kept apart by the subtle balance of attractive and repulsive forces 

 with a slight predominance of repulsion. These repulsive forces 

 are electric and the ATP (linked to myosin), plays, with its four 

 negative charges, a leading role. This balance of forces is de- 

 stroyed, for an instant by "excitation," whereupon actin and myo- 

 sin form actomyosin. In the actomyosin thus formed the terminal 

 '-^P of ATP becomes split and its energy put to action. Relaxation 

 involves the rephosphorylation of the ADP into ATP which, with 

 its four charges restored, pushes actin and myosin apart whereupon 

 the free myosin particles rebuild their water structures and stretch 

 out into filaments again, thus becoming ready for a new contrac- 

 tion. 



The theory outlined also finds support in the fact that no fold- 

 ing was hitherto revealed in contracting actomyosin filaments by 

 the electron microscope. All one can see (as shown beautifully in 



