Page:Life in Motion.djvu/115

Rh it to say that it is a very complex structure, containing apparently contractile matter in the form of discs alternating with discs of a substance that is not contractile but which may

possibly be elastic. Further, during life, the whole of this remarkable structure is semi-fluid, and there are good grounds for believing that the contractile action is due to the creation of currents passing from one part of the fibre to another, accompanied by chemical changes of a very complicated kind.

As one would expect, the fibres of muscle are intimately connected with a nerve. But