On muscular Motion. 223 



rtegar, nor v/ater saturated with muriate of soda, nor strong 

 ardent spirir., nor olive oil, had any such effect upon the 

 Eiuscular fibres. 



The amphibia, and coleopterous insect?, become torpid 

 at 34°: at 36" tJiey move slowly, and with difficulty; and 

 at a Jt:)\ver temperature their muscles cease to be irritable. 

 Tlie muscles of warm-blooded animals are similarly affected 

 by cold. 



The hinder limbs of a frog were skinned, and exposed to 

 cokl at 30°, and the muscles were kept frozen for eight 

 hours; but on thawing them they were perfectly irritable. 



The same process was employed in the temperature of 

 20", and tlie muscles kept frozen for twelve hours j but 

 thiit did not destroy the irritability. 



In the heat of 100", the muscles of cold-blooded animial^ 

 fall into the contractions of death ; and at 1 10", a!) those of 

 warm blood, as far as these experiments have been extended. 

 The muscles of warm-blooded animals, which always con- 

 tain more red particles in their substance than those of cold 

 blood, are soon deprived of their irrit:.bility, even although 

 their relative temperatures are preserved ; and re-piration in 

 the former tribe is more essential to life than in the latter. 



Many substances accelerate the cessation of irritability in 

 muscles when applied to their naked fibrils, such as all the 

 iia5-cotic vegetable poisons, nmriate of soda, and the bile of 

 animals ; but they do not produce any other apparent change 

 in muscles than that of the last contraction. Discharo-es 

 of electricity passed through muscles, destroy their irrita- 

 bility, but leave them apparently inflated with small bub- 

 bles of gas ; perhaps some combination obtains which de- 

 composes the water. 



The four separated limbs of a recent fros; were skinned, 

 and immersed in different fluids ; viz. No. 1. in a phial con- 

 taining six ounces, by measure, of a saturated aqueous so- 

 lution of liver of sulphur made with potash; No. 2. in a 

 diluted acetic acid, consisting of one drachm of concentrated 

 acid to six of water ; No. 3. in a diluted alkali, composed 

 of caustic vegetable alkali, one drachm, of water six ounces; 

 No. 4. in pure distilled water. 



The phials were all corked- and the temperature of their 

 contents was 46". 



The limb contained in the phial No. 1, after remaining 

 twenty minutes, had acquired a pale red colour, and the 

 nniscles were liighly irritable. 



The limb in No. 2, after the same duration, had become 



rigid, white, and swollen ; it was not at all irritable. By 



2 removing 



