110 WARFARE IN THE HUMAN BODY 



state the whole tool remains more or less rigid. On 

 receiving stimulation in a normal condition of the myo- 

 cardium it is assuredly a case of " all or nothing," for a fibre 

 cannot really move by itself, although in the pathological 

 state of fibrillation there are useless unco-ordinated 

 twitches. Even if I were qualified to enter into the whole 

 question of muscular action, and most assuredly I am not, to 

 do so would be unnecessary in this question of the diastole. 

 It is sufficient to note that there appears a fairly general 

 consensus of opinion that contraction is due to surface 

 action, and that, though oxygen is needed for the energy 

 which restores potential, combustion takes no part in the 

 actual work done. We are here, however, not concerned 

 with contraction, but with elongation, and, though it is diffi- 

 cult to understand in what way osmosis plays a part, it is 

 known that in muscle action there is movement of water 

 (Bayliss), and that fatigued muscle readily absorbs it. It 

 may, perhaps, be said that during contraction the water is 

 expelled into " lakes " in the interstices of the network 

 of cells, that during the refractory period the oxidative 

 processes which restore lactic acid take place, and that 

 elongation is osmotic expansion. Thus contraction has an 

 outflow and elongation an inflow, which, it may be suggested, 

 puts the whole process on a par with vaso-constrictor 

 and vaso-dilator phenomena. If this is so it seems 

 perfectly legitimate to regard the muscle cells as complex 

 sets of reversible hydraulic presses, and to infer that, 

 though apparently less powerful than contraction, length- 

 ening of muscle is a process exactly analogous to vaso- 

 dilatation. That this process may be increased by normal 

 stimulation of the vagus centre can hardly be doubted, 

 and when it is said that the vaso-dilator centre is not yet 

 discovered, though known to exist since vaso-dilator 



