10 ENERGY TRANSFORMATIONS 



Take, as an example, the nerve impulse travelling along a 

 living nerve-fibre. A similar phenomenon cannot be reproduced 

 in any non-living structure, and while it is accompanied by an 

 electric wave which travels at the same rate, it cannot be held 

 that the electrical energy is the nerve impulse, any more than 

 that the chemical change or electric wave accompanying a 

 muscle contraction wave is the contraction wave itself ; or, to 

 choose an example from energy transformation in non-living 

 matter, that the heat in the wire, and magnetic field around it, 

 are the electric current travelling along the wire. In many 

 other manifestations of irritability than the nerve impulse it is 

 known that increased electrical negativity is associated with 

 increased physiological activity, and hence the most logical view 

 certainly is that the negative wave accompanying the nerve 

 impulse betokens a wave of increased irritability propagated 

 along the fibre. Here we have, then, a phenomenon of biotic 

 energy in a typical form, and can even get at one property, namely, 

 the rate at which the wave of biotic energy is carried along 

 this particular type of conductor. In the muscle cell a similar 

 wave is seen traversing a different form of conductor at a 

 different rate. 



V. The metabolism of the cell furnishes further proof that 

 energy changes in the cell are produced by the action of a type 

 of energy not found elsewhere than in living tissues. The pro- 

 duction of the living protoplasm of the cell itself has already 

 been alluded to as a proof of the existence of such a type of 

 energy ; but in addition to the substance of the energy-trans- 

 former itself, there are to be considered the products formed 

 interstitially within the cell. Most of these are so complex that 

 they have not yet been synthesised by the organic chemist ; but 

 even of those that have been synthesised, it may be remarked 

 that all proof is wanting that the syntheses have been carried 

 out in identically the same fashion and by the employment of 

 the same forms of energy in the case of the cell as in the 

 chemist's laboratory. The conditions in the cell are widely 

 different, and at the temperature of the cell and with such 

 chemical materials as are at hand in the cell no such organic 

 syntheses have been artificially carried out by the forms of 

 energy extraneous to living tissue. 



Again, the regulation of the production and breaking up of 



