440 ELECTRICITY IN THE PHENOMENA OF ANIMAL LIFE. 



eses, and let us esijecially coinpaio the yield in niucluniical energy of 

 a tlierniic or electric motor with that of a living- motor. 



We know that the most highly approved thermic motors do not give 

 more than about 8^ i)er cent of useful effect; the theoretic limit to the 

 yield of steam engines is 17 per cent, and to that of gas engines 21 per 

 cent. On the other hand, let us look back to the experiments of Iliru 

 and Ilelmholtz. We find that we must assign to the yield of a muscle 

 a mean value of more than 30 per cent. 



It is impossible, as wo see, to compare with this useful effect tlie far 

 inferior yield of the thermic motors of human contrivance; the dilTer- 

 ence is so great that, without reference to certain physical impossibil- 

 ities pointed out by Ilirn, it suffices to make us give up the hypothesis 

 of a thermic cause, in the sense in which we have just spoken of it. 

 The idea of electrical transformation presents itself in (juite a different 

 light, since in this case the yield in dynamic effect is much greater and 

 is comparable to that of the living motor. 



II. — OF THE SKAT IN THE ANIMAL BODY OF KLECTKICAL MANIFESTATIONS. 

 ELECTKOGENIC APPARATUS. 



- - - Oxidation of organic matter takes place in all the living cells. 

 It takes place even in the blood and in the lymidi at the ex[)ense of the 

 chemical constituents carried forward by these lluids and not as yet 

 endowed with organized structure. All the tissues take part in this 

 process of internal combustion. All must tlius co)itribute to the supply 

 of energy necessary to the living being. 



But the relative importance of each of the tissues varies greatly in 

 this respect. To convince ourselves of tliis we need but, for instance, 

 contrast the i)hysiology of muscular tissue with that of connective 

 tissue. 



The preponderant importance of the i)art played by muscular tissue 

 is manifest; we know, in fact, that when work is being done the mus- 

 cles come in for some 70 or 80 per cent of the total oxidation taking place 

 in the animal economy. The glands, which rei)resent apparatus com- 

 posed of cells of great vital activity, also undergo rapid oxidation. 

 Internal oxidation is for us the source of electricity. This process goes 

 on chiefly in the nuiscles and in the glands; hence we give to these 

 portions of the whole organic structure the name of electrogenic 

 apparatus. 



It is interesting to notice that the tissues which are the seat of most 

 active oxidation, as the muscles and the glands, are richly jirovided 

 with nerves, while those in whicli oxidation is feeble, as the cartilages 

 and connective tissue, are but poorly sui»i)lied by the nervous system. 



May we not use this fact — a very important one, in my opinion — to 

 establish an analogy between each animal organism, simple or com- 

 l»lex, amaba or man, and the cell or single element of a voltaic battery"? 

 Thus the readily oxidizable tissues, forming the electrogenic apparatus, 



