208 ANIMAL FORCES. [ii. 



whole, that no one has been able hitherto to trace them to 

 their terminations, it follows that it is impossible to separate 

 the muscular fibrils from the nerve-fibrils, and so afford the 

 proof required; so that when it is affirmed, that a muscle 

 retains its animal force after being separated from its nerves, 

 it is first of all necessary to show how this separation has been 

 eff'ected. 



381 . The trunks of the nerves distributed to a muscle have 

 been divided, and the latter have nevertheless been excited to 

 movement by an external irritant. Is this the required proof? 

 Certainly not. The division of the trunks does not destroy 

 the infinitely numerous twigs distributed to the muscle, and so 

 long as it retains these, the vis nervosa is incorporated with 

 it. Further : 



i. Nerves retain their purely animal motor force derived 

 from external impressions from the point of impression to 

 the point of bisection (357, 358). So long, therefore, that it 

 cannot be shown, that the irritant which moves a muscle after 

 its nerves have been divided, cannot act impressionally on the 

 nerve-twigs in the muscle, and that the animal movement in 

 the latter is not excited thereby, the peculiar animal force of 

 the muscular fibre is not demonstrated by the experiment. 

 Consequenth^, although the movement of a heart separated 

 from the body be renewed and increased by puncture with a 

 needle, by acrid irritants, by injections of water, &c., still this 

 does not prove that the irritation induced this activity through 

 the muscular fibrils only, without the co-operation of the 

 nerves, for it is incontrovertible that it can produce them in 

 virtue of the impression on the nerves of the heart, because 

 every point of a muscle, and consequently of the heart, both 

 its inner and outer surface, which the needless point touches, 

 can, in the healthy state, so receive the irritation, that it is 

 felt, which is only possible by means of nerves ; while further, 

 the same increased activity of the heart results as an animal 

 action excited by the external impression which this irritation 

 causes, whether it goes to the brain or not (357, 358). 



ii. The nerves retain also their vis nervosa, excited by non- 

 conceptional internal impressions from the point of impression 

 (whether it be at the origin of the nerves, or on their trunks), 

 to the terminating fibrils (359, 360). When, consequently, the 



