KNKR(; ) ' TR. I XSrORM EHS 1 C,7 



are not a maiiiiracturing community but are power users. In 

 another sense, the nmscles are the servants t)!" the body. By 

 means of them, the body fights a war not merely of defence but 

 of aggression against its environment. As civihsation has ad- 

 vanced, man has found it convenient by means of tools and 

 machines to add power and speed to his muscle. By so doing, he 

 has been able to harness and utilise power from sources that could 

 not have been tapped otherwise. Tools and machines are thus 

 extended and detachable limbs. 



The Muscles are Energy Transformers. In the first instance, they 

 act as accumulators accepting energy principally in two forms [e.g. 

 potential energy of glucose and osmotic energy of glucose, phos- 

 phates, etc.) and then storing that energy in potential form (in a 

 glycogen-nitrogen-phosphorus compound having a very low osmotic 

 pressure) till it is required, when it is liberated (in what form we do 

 not know) and converted into kinetic energy. That is, muscle is a 

 compound transformer, [a) It stores energy and, just like any 

 other accumulator, the amount of energy stored depends on the 

 size and number of the units, and the potential of the energy 

 released only on the number of units composing the muscle. When 

 a muscle has its full charge, it can take no more. The amount of 

 glycogen stored in muscle is definitely limited by the bulk of the 

 muscle for each particular type of muscle, (b) On activation, it 

 transforms portions of the stored energy into some form which 

 acts on the liquid colloidal mass within the fibres, causing the mass 

 to become less liquid and more viscous, and producing a shortening 

 and thickening of the muscle as a whole, (c) This latter process, 

 on account of the attachment of one end of the muscle to a fixed 

 point and the other end to a lever system, results in the perform- 

 ance of work. The muscle may now relax, and, after the lapse of a 

 suitable period, again undergo shortening, and so on, once every 

 five minutes or so, for about fifteen hours, before markedly showing 

 any sign of the accumulator running dow^n. This feat can be 

 performed in an atmosphere of nitrogen, thus excluding the 

 oxidative removal of the bye-products of the reaction. If one 

 attempted to get not only maximal discharges of energy, but tried 

 to get them as quickly as possible, one after the other, the accumu- 

 lator would show signs of weariness very early — whether it were one 

 of cellulose, lead, acid and water, or one of protein, polysaccharide, 

 lipide, water, etc. 



This double process of contraction and relaxation can be carried 

 on quite readily without oxygen, but the next stage, that of 

 recovery — re-charging the storage battery — can only be effected 

 efficiently in the presence of oxygen and circulating water contain- 



