M. Flourens om the Nervotis System. 115 



This property, to which Ghsson and Frederic Hoffiiian had 

 ah-eady directed the attention of observers, became towards the 

 middle of the eighteenth century, the object of the numerous 

 experiments of Haller, and was known under the name of Ir- 

 ritability. 



These experiments showed that this property of forcibly 

 contracting, either from immediate irritation, or in consequence 

 of the irritation of the nerve, exists in the muscular fibres ; 

 and that it exists in no other element of the animal body. 

 Their importance excited a lively interest; the disciples of 

 this great physiologist repeated them, and indeed exaggerated 

 their effects. 



As the irritability is not in proportion to the size of the 

 nerves which are distributed to each muscle, and as it was then 

 believed that there existed muscular parts entirely or almost 

 entirely devoid of nerves; some physiologists concluded that this 

 property belongs to the fibre itself, independently of its con- 

 nexion with the nerve; that the nerve may be one of the irri- 

 tating agents, but that the other irritants would act without it. 

 It would, however, be wrong positively to attribute this opi- 

 nion to Haller himself. Many passages in his writings show 

 very distinctly that he was by no means ignorant of the co- 

 operation of the nerve in the phaenomena of irritability ; and 

 the more these phaenomena are studied, the stronger will be 

 the conviction of that cooperation. Now that the nerves of 

 all the muscular parts are known, that no muscular fibre can 

 be conceived which has not some connexion with a nervous 

 filament, nobody would venture to maintain that this nervous 

 filament remains passive during the contraction. The only 

 thing incontestably proved, is, that the contraction may take 

 place independently of all sensation in the animal, and of all 

 volition which that sensation may have produced. 



Now this latter proposition, which Haller first placed in a 

 clear light, and the natural application of it which he made 

 to involuntary motions, such as those of the heart and viscera, 

 completely overturned a physiological system long in vogue, 

 I mean that of Stahl, which made the soul the author of all 

 the motions of the body, not only of those which we perceive 

 and will, but even of those of which we have no consciousness. 

 Stahlianism, already forgotten in Germany, where systems 

 disappear as rapidly as they arise, had just been introduced 

 at Montpellier by Sauvage. An attempt was made to defend 

 it against the school of Haller; but this apparent defence was 

 made only by distorting the system, and introducing into the 

 language of physiology an innovation which for a long time 

 beemud to render that science not oiilv the most diflicult, but 

 V 'J * the 



