Chap, in.] OF MOVEMENTS IN THE ANIMAL KINGDOM. 369 



This fact is observed alike in the striated fibres and the smooth 

 fibres. But according to the observations of M. Dubois-Eey- 

 mond the intensity varies in the different muscles. It seems 

 therefore certain that every muscular fibre is electrised positively 

 at its surface, and negatively at its centre. 



At the moment when the muscle enters into the state of 

 cadaveric rigidity, the current is interverted ; it ceases finally 

 when the fibre commences to decompose. 



In like fashion the heart of a frog is electrised, positively at 

 its point, and negatively at its base. Similar phenomena are 

 observed, moreover, in the nervous fibres, and analogous ones 

 have been observed in vegetal fibres. We must content our- 

 selves with mentioning in passing these cuiious facts, of which 

 no satisfactory scientific explanation has yet been given. ^ 



Of all the excitants of muscular contractility, which we 

 have just passed under review, there is none which equals in 

 power the special physiological excitant, the nervous fibre. 

 The excitants, not themselves physiological, act on the muscle 

 with a hundred-fold energy when they borrow the aid of the 

 nervous threads which are distributed in the muscle. It results, 

 in effect, from the observations and the measurements of 

 Matteucci, that during its contraction a muscle accomplishes a 

 mechanical labour at least 27,000 times greater than the chemical 

 labour, whence has come the excitation of the nerve. ^ Now in 

 the complex animals all the muscles receive nervous fibres, con- 

 nected with the central nervous system, and the influence of 

 these nervous centres on the muscular movements is the greater 

 the more perfect the animal is. But in order to form an idea of 

 the relations of the muscular system and the nervous system, it 

 is indispensable to study the last and the noblest of the general 

 properties of organised matter, that is to say, innervation, 



' 01. Bernard, loc. dt., pp. 205, 207, 



" Matteucci, TMorie Dyna/mique de la Ghaleur [Hevue Scimtifique, 1866, 

 n". 51. 



