AND ANIMAL LIFE. 261 



to reside in and characterise muscular fibre is de- 

 rived from the nerves of motion and sensibility. 

 This power is very much modified by three 

 causes: 1. The quantity of nervous influence posses- 

 sed by an organ ; 2. The disposition of the muscular 

 fibres ; 3. The nature of the stimulus necessary to 

 develope it. The heart has been proved by SCARPA 

 to be endowed with innumerable nervous fibrillae, 

 not confined, as was imagined by SOEMMERING 

 and his predecessors, to the coats of the coronary 

 arteries, but, on the contrary, intimately blended 

 with the constitution of the fibre itself. If we 

 consider the quantity of nervous power bestowed 

 upon the heart by the sympathetic and par 

 vagum, the disposition of the fibres and cavities 

 of this organ, and, lastly, the energetic and con- 

 stant stimulus operating here, we shall under- 

 stand in what manner the contractions of an 

 organ may be influenced. 



CCLXXXII. There were two objections op- 

 posed to the opinion of HALLER. The first ivas, 

 for what purpose did the heart receive nerves? and 

 the second, why was it influenced by strong emotions 

 of mind ? The first is a difficulty which was never 

 satisfactorily solved by HALLER, and the latter 

 is considered equally unanswerable by the op- 

 ponents to the vis insita of this physiologist. 

 Although I am fully persuaded that the con- 

 tractions of the heart are to be ascribed to the 

 nervous power distributed to the muscular fi- 



