. OF THE MUSCULAR SYSTEM IN GENERAL. 421 



and research on the part of Haller, of several physiologists 

 anteripr to him, and of a great number of his cotemporaries 

 and of his successors. 



The study of the muscular action comprehends: 1st, that of 

 the phenomena of this action; 2d, that of its. conditions; 3d, 

 that of its principle or. cause, and 4th, that of its effects. 



669. The phenomena of the muscular action which are 

 best known are the following: the muscle in action becomes 

 shortened, tumefied, hardened; we are uncertain whether or 

 not its volume "changes; its colour does not vary; it presents 

 wrinkles or folds on its surface; its fibres and fasciculi are 

 often in a tremulous or oscillating state depending on its alter- 

 nate contraction and relaxation: it acquires great force and 

 manifest elasticity: these are the phenomena of contraction; 

 the most remarkable of these facts indeed, is the shortening of 

 the muscle. When the action ceases, all these phenomena 

 disappear, and the muscle is then in a state of relaxation. 



torn. ii. Haller, departibuscorp. ham. irriiabiKbuSf in comm. Getting, torn, 

 ii, et in nov. comm. Getting 1 , torn. iv.-&M?moires sur la nature sensible et irri- 

 table des parties du corps humain. Laus. 1756-59. Petrini, sull 'inscnsib. e 

 irritab. dissert- transp. Iloma, 1754. Fabri, sull insensitiva e irrit. opulscol. 

 raccolti.; Bonon, 1757-59. A. G. Weber, de initiis acprogr. doctr. irritnb., 

 etc, Halx, 1783. J. L. jGautier, (prses. JReil.} da Irritabil. notione, etc. 

 ftalx, 1793. Croonian-^ lectures on muscular motion, in Philos. Trans. 1738. 

 1745, 1747, 1751, 1788, 1795, 1805, 1810, 1818, &c. J. Chr. A. Claras, 

 der Krampf. Lips. 1822. Lucae, G-rundlinien einer physiol. der irrilabilitat 

 des menschlicheu organismus, in Mechel's Arcli. B. iii. G. Blane, On muscu- 

 lar motion,- Lond. 1788, et in select. Dissert., etc. Lond % 182%. : BarzeJotti, 

 Esamc di alcune moderne teorie alia causa prossima della contrazione musco- 

 lartj Sienna, 1796, et in ReiPs Jirchiv. B. vi. H. Mayo, Anal, and Physiol, 

 commentaries) No. 1. Lond. 1822. 



f Dr. W. Croone, who died in 1684, left the plan of two lectures to be 

 instituted, the .one at the Colleg-e of Physicians, on the nerves and brain: 

 the other, which was to be annual, at the Royal^ Society of London, on the 

 nature and laws of muscular motion. The latter is still continued, and has 

 given rise to several excellent papers, both on the texture and action of 

 the muscles. Several of these lectures are not consigned in the Philosophi- 

 cal Transactions. 



