©'25' Ofi muscnlar Matio'Tt. 



fustratetJ by the instances of compression upon f tie varun-' 

 taiy muscles, when partiallv contracted, of which there are. 

 many famiHar examples. Probably the muscles of the ossi- 

 cula auditus- are awakened by the tremors of sound ; and' 

 this may be the occasion of th'C peculiar arrano-cment ob" 

 servable in the chorda tympani which serves tho^se muscles'. 



These extraneous stinrulr seem only to act in conjunctiou 

 ■U'ith the sensorial power derived by those muscles from th.c 

 ganghated nerves, because the passions of the mind alter 

 the muscular actions of the heart, the alimentarv canal, tire 

 respiratory muscles, and the iris ; so that, probab'ly, the re- 

 spective stimuli already enumerated, only act subservientlj', 

 by awakening the attention of the sensorial power, (if that 

 expression may be allowed',) and thereby calling forth the 

 nervous iniiuenee, which, from- the peculiar or2;anization 

 of the great chain of sympathetic- nerves, is effected without 

 consciousness ; for, when the attention of the mind, or the 

 more interesting passions prevail, all the involuntary mus- 

 cles act irregnlarly and unsteadily, or wholly cease. The 

 movements of the iris of the common parrot are a strikintj 

 example of the minted influence. 



The nmseles of the- lower tribes of anin>als, which arc 

 often entirely supplied bv nerves coming from ganglions, 

 appear of this class j and thus th-e animal motions are prin- 

 cipally regulated by the external stimuli, of which the oc- 

 currence seems to agree with the animal necessities : bnt 

 the extensive illustrations- which comparative anatomy af- 

 fords on this- point, are mach- too copious- for any detail in 

 this place. 



There are two slates of mtrsclcs j one active, which is that 

 of contraction ; the other, a state of ordinary tone, or re- 

 laxation, which may be considered passive, as far as it re- 

 lates to the mind; but the sensorial or nervous power seems 

 never to be quiescent^ as it respects either the voluntary 

 or involuntary muscles during life. The yrelding of the 

 sphincters appears to depend on their being overpowered by 

 antagonist muscles, rather than on vo-kmtary relaxation, as 

 is comr/ronly supposed. 



I have now tinJshed this endeavour to exhibit the more 

 recent historica} facts conrtectcd with muscular motion. 



It will be obvious to everyone, that much remains to be 

 done before any adequate theory can be proposed. I hav(i 

 borrowed from the labours of others without acknowledg- 

 ment, because it would be tedious to trace every fact, and 

 every opinion, to its proper authority ; manv of the views 

 are perhaps peculiaF to myself, and I have adduced many 

 4 general 



