142 Traces of Unity in 



action of artificial electricity upon muscle, for in the 

 latter case it is found, not only that charge acts in the 

 same way in causing muscular elongation, but also that 

 the elongation is proportionate to the charge, and that, 

 the extra-contraction in electrotonus is only the simple 

 result of the muscle in this particular case having had to 

 return from a state of extra-elongation consequent upon 

 a state of extra-charge. 



Nor does the consideration of rhythmical vital 

 motion as manifested in cardiac muscle or elsewhere lead 

 to a different conclusion. In ordinary muscle, unless the 

 muscle be interfered with in one way or another, the 

 natural charge is kept up steadily : in the muscle which 

 is naturally the seat of rhythmical action, on the 

 contrary, the natural charge, instead of being kept up 

 steadily, fails periodically, and so leads td tlie develop- 

 ment of the instantaneous currents of high tension by 

 which periodical contraction is brought about. The 

 natural electricity is evidently maintained for a longer 

 time in the former case than in the latter. And why ? 

 Is it that there is in the two muscles a molecular 

 difference analogous to that by which a piece of 

 paraffin charged by friction will retain its charge for a 

 longer time than a piece of glass so charged ? Is it 

 that irt the case of the muscular fibres of the heart or 

 air-passages, the state of rest corresponds to the time 

 during which there is enough oxygen in the arterial blood 

 ^vithin the vessels of the heart, and in the air within the 

 air-passages, to keep up sufficient charge in the fibres to 

 inhibit the contraction which in due time drives out the 

 used-up blood from the vessels, or the used-up air from 

 the air- passages, and, by so doing, prepares the way for 

 the admission of fresh blood and air into the vessels 

 and air-passages, and for the restoration' of the state of 



