250 ®^ MUSCULAR MOTION. 



but not by acid vitiftg^ar, nor water faturated with muriate of foda, nor ftrong 

 or faiinc water, ardent fpirit, nor olive oil, had any fuch efFed upon the raui- 



cular fibres. 

 Cold renders Tlie amphibia, and coleopterous infeQs, become torpid at 



mufclcs torpid. 3^0^ ^t ^qo t|,e^ n^oye ^^^^^^ ^^^ ^j^h difficulty ; and, at a 



lower temperature their mufcles ceafe to be irritable. The 

 mufcles of" warm-blooded animals are iimilarly affe6led by 

 cold. 

 Mufcles of frogs The hinder limbs of a frog were Ikinned and expofed to 

 frcMing.^^^''' cold at 30°, and the mufcles were kept frozen for eight hours, 

 but on thawing them, they were perfedlly irritable. 



The fame procefs was employed in the temperature of 2^. 

 and the mulicles kept frozen for twelve hours, but that did not 

 deftroy the irritability. 

 Heat deprives In the heat of 100*^, the mufcles of cold-blooded animals 



P"^'^^^" o^/^""^ fall into the contraaions of death; and at 110°, all thofe 

 of warm blood, as far as thefe experiments have been ex- 

 tended. The mufcles of warm-blooded animals, which always 

 •* contain more red particles in their fubllance than thofe of 

 cold blood, are foon deprived of their irritability, even aU 

 though their relative temperatures are preferved ; and ref- 

 piration in the former tribe is more eflential to life than in the 

 latter, 

 as do poifons, Many fubftances accelerate the ceflation of irritability in 



mufcles when applied to their naked fibrils, fuch as all the 

 narcotic vegetable poifons, muriate of foda, and the bile of 

 animals ; but they do not produce any other apparent change 

 and clearicity. i" mufcles, than that of the laft contra6lion. Difcharges of 

 eledricity patfed through mufcles, deftroy their irritability, 

 but leave them apparently inflated with fmall bubbles of gas ; 

 perhaps fome combination obtains which decompofes the 

 water. 

 Experiments oa The four feparated limbs of a recent frog were ftinned, and 

 mufcles im- immerfed in different fluids; viz. No. I, In a phial containing 

 nier e in ui s, ^^ ounces by meafure of a faturated aqueous folution of liver 

 of fulphur made with potafli; No. 2, In a diluted acetic 

 acid, confifting of one drachm of concentrated acid to fix of 

 water; No 3, in a diluted alkali, compofed of cauftic vegetable 

 alkali one drachm, of water fix ounces; No. 4-, in pure dif- 

 tilled water. ' 



Ths 



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