286 The Older Doctrines [lect. 



" of the nerves to a muscle, caught up by the membranaceous 

 a fibrillar, and carried by means of these to the fibres of the 

 " tendon, are then plenteously stored up as it were in suitable 

 " storehouses. These spirits, being by nature exceedingly active 

 "and elastic, upon expanding as their power and opportunity 

 "permit, leap into the fleshy fibres, and presently afterwards, 

 " their impetus being exhausted, falling back, they retreat again 

 " into the tendons ; and this is repeated again and again. When 

 " however the animal spirits at the bidding of the instinct to 

 "bring about movement rush from the tendinous to the fleshy 

 "fibres, they there meet with active particles of a different 

 " nature supplied by the blood, and forthwith the tw r o mixing, 

 "effervesce, so that out of the struggle and agitation of the 

 "two, the fleshy fibres, previously lax and porous, are stuffed 

 "full and thrown into corrugations, and all the fibres being 

 " thus corrugated at the same time, the contraction of the whole 

 " muscle is brought about. The contraction being finished, the 

 " pure spirits which remain for the most part retreat again 

 "into the tendinous fibres, the remaining particles being left 

 " among the fleshy fibres. The loss which has occurred among 

 " the latter is made good by the blood, that among the former 

 " by the nerves." 



Mayow, as we have seen, had his own view about the matter 

 in question. He like many other discoverers who have laid hold 

 of a great truth, but have not had time to go all round it, was 

 inclined to see in his spiritus nitro-aereus, an explanation of 

 nearly all the unexplained phenomena of the universe ; he used 

 it to explain muscular contraction. This was in his view a 

 fermentation set up between the combustible, sulphurous 

 particles residing in the muscle, and the nitro-aereal spirit 

 brought to it by the nerves. But he got no further than 

 this. 



While these several men of the seventeenth century whom 

 I have just mentioned were hovering about the truth of the 

 relation of nervous influences to muscular contraction, some 

 getting more, others less near, one among them, an English- 

 man, came upon the truth itself, and after him this part of 

 physiology stood still for near a hundred years. This was 



