134 ENERGY TRANSFORMATIONS IN LIVING MATTER 



tability propagated along the fibre. Here we have, then, a pheno- 

 menon 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 transformer 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 

 such substances, the variations in rate of action, and the regulation 

 of the manifold intercurrent reactions running simultaneously 

 within the minute compass of a single cell, even more powerfully 

 than the mere synthesis of the substances point to a controlling 

 and regulating type of energy different from anything outside living 

 matter. The reversal of chemical action from period to period, 

 and the sudden changes in chemical activities produced by the 

 activity of the nervous system, have no parallel outside the realm 

 of living cells. 



Much has been made of the fact that intracellular enzymes 

 have been isolated from living cells which are capable of producing 

 actions hitherto only observed in the presence of the cell, and it has 

 been surmised that all or nearly all the chemical activity of the cell 

 may be due to the action of a large number of such intracellular 

 enzymes. It has, in fact, been supposed that if a solution could be 

 prepared containing the proper number of enzymes, each in appro- 

 priate concentration, the solution would act much like a cell. 



