74 Borelli and the Influence [lect. 



"contrary movements are brought towards each other, the 

 "muscle swelling and enlarging in breadth." 



After pointing out the various difficulties he says, " Finally 

 " a very common experiment does away with all this nonsense 

 "about air. When the muscles of a living animal are divided 

 " lengthwise, while the animal is submerged under water, and in 

 " consequence of the pain is struggling violently in the midst 

 "of such great copious fervour and ebullition of the supposed 

 " spirituous gas which would thereby be excited in the muscles, 

 "one would expect that innumerable bubbles of gas would 

 "burst forth from the wound, and ascend through the water, 

 "whereas nothing of the kind takes place." 



He further goes on to shew that vital contraction cannot 

 take place by reason of any juice or blood distending the 

 porosities of the muscles, nor from the blood being driven into 

 them by the force of the heart. 



Having thus discussed the wrong explanations, he proceeds 

 to expound the probably true explanation of muscular con- 

 traction. 



He concludes that for bringing about muscular contraction 

 two causes are necessary, one existing in the muscle itself, 

 the other brought to it from without. 



" Since all muscles, with some few exceptions, do not 

 " manifest vital movement otherwise than in obedience to the 

 " will, since the commands of the will are not transmitted from 

 " the brain which is the instrument of the sensitive, and the 

 " seat of the motive soul, by any other channels than the nerves 

 " as all confess and as the most decided experiments shew, and 

 "since the action of any incorporeal agency or of spirituous gases 

 "must be rejected, it is clear that some corporeal substance 

 "must be transmitted along the nerves to the muscles or 

 " else some commotion must be communicated along some 

 " substance in the nerves, in such a way that a very powerful 

 " inflation can be brought about in the twinkling of an eye. 



"And since the inflation, hardening, and contraction do 

 " not take place in the channels which serve for bringing them 

 " about and in which the motor influence resides, namely, in the 

 " nerves themselves, but takes place outside the nerves, namely, 



