VOL. LXXVIII.J PHILOSOPHICAL TRANSACTIONS. 365 



set forth : yet it is clear from every experiment made on the subject, that all 

 motion arises from particles coming near one another in some direction. It 

 would be superfluous to point out these experiments; I shall mention one only, 

 and an obvious one. Lay bare a muscle, and prick any of its fibres, it ir"'^^- 

 diately becomes shorter. 



The original power of coming nearer to one another of 2 or more particles of 

 matter, has been called attraction. There have been several original powers of 

 coming nearer one another of particles of matter, which have been considered as 

 different attractions, such as the attraction of gravitation, of magnetism, of electri- 

 city, &c. The attraction which ismy present object, Icall the attraction of life. This 

 attraction is either of 2 species, or is exerted variously; for all the moving parts 

 have their particles nearer one another in the living than in the dead body. The 

 proof of this is as necessary as it is obvious. Take the body of any animal, 

 when the life is entirely gone from it, and the effects of it are entirely lost, but 

 before any putrefaction, or any change in its chemical qualities, has taken place; 

 and lay bare, and dissect out, any muscle, especially one which has long fibres, 

 and no middle tendon, such as the sartorius, for example, and afterwards lay it 

 in its place, leaving it of the length it naturally takes; it will reach farther than 

 from its origin to its insertion; but lay bare, and dissect out, the same muscle 

 in the living body, and it will always be shorter than from its origin to its in- 

 sertion. If it should be said, that the dissection stimulated the muscle, and 

 brought it into action, let it not be dissected out, but its tendon cut through, as 

 the tendo Achilles, for instance, the same thing will happen. And we now are 

 all convinced, from various experiments, that a tendon in a sound state is not 

 capable of being stimulated by being wounded, cut through, or broken. 



I apprehend then that we may conclude, that all the moving parts are con- 

 stantly contracted, that is, their particles are nearer one another when the body 

 is alive, than when dead, and totally left to their elasticity. This species of 

 action I call the tone. The 2d species, or variety, which occurs in the at- 

 traction of life, is when a moving part, for a short time, has its particles brought 

 nearer one another than they are from their tone, and which very rarely con- 

 tinues for many seconds of time without intermediate relaxation. I call it their 

 action; when it continues for a longer time, it is called spasm; which however 

 is so vague a term, that I could wish totally to reject it, at least to confine it 

 only to this sense, viz. a greater contraction, or coming nearer one another of 

 the particles, of a moving part, than that which would happen from their tone, 

 remaining without any intermediate relaxation. 



For the present I do not mean to say any thing further with regard to the tone, 

 or spasm of parts; but only to consider the action as excited by applications to 

 some part of the body at a distance from the moving part. I have already re- 



