x] of the Nervous System. 283 



" convulsive irritation, can squeeze out and discharge from their 

 " extreme orifices some spirituous droplets into the appropriate 

 " muscle, whence the ebullition and explosion follow by which 

 " the muscle is contracted and rendered tense. 



" And on the other hand when the extremities of the sensory 

 " nerves which end in the skin, nose, ears or eyes, are compressed 

 " or struck or titillated, it necessarily follows that forthwith the 

 "concussion, undulation, or titillation of the spirituous juice 

 " contained within the tubules is conveyed along the whole 

 " length of the nerve and reaches the particular part of the 

 *' brain to which the nerve fibres are joined. And here the 

 " faculty of the sensitive soul according to the region of the 

 " brain thus percussed, according to the vehemence of the blow 

 "and the fashion and mode of the motion, is able to form a 

 "judgment concerning the object causing the movement." 



He expressly declares that the "juices, however spirituous 

 " and active, are always corporeal and cannot act at a distance, 

 "and cannot, without physical contact, increase, intensify, or 

 " depress the animal spirits ; it is by means of their corporeal 

 "presence that they either increase the animal spirits which 

 " are also corporeal, mixing themselves with them, or expel 

 " them, or transform them. Wherefore it cannot be conceived 

 " that nervous action can take place without some local move- 

 " ment of the nervous juice passing along the whole length of 

 " the nerve right to the brain." 



Borelli's view of nervous action therefore was a strictly 

 physical one ; in voluntary movement the concussion of the 

 nervous fluid started at the brain, and passing along the whole 

 length of the nerve, led to the ejection of some droplets of the 

 fluid into the substance of the muscle, and thus gave rise to 

 contraction. Of the act of contraction itself he was inclined to 

 take a chemical view, to believe that the inflation of a muscle, 

 which according to him was the essence of contraction, was 

 brought about " by something like a fermentation or an 

 " ebullition " ; but of this he speaks guardedly. 



Stensen, as we have seen, though he nowhere dwells on the 

 exact nature of nervous action or its relation to muscular con- 

 traction, had arrived at conceptions of the nature of muscular 



