STATE OF MUSCLES IN ACTION. 



399 





Muscular Fibre of Skate. 



In a state of rest (1), and in three 

 i of contraction (2, 3, 



nouilli and Keill 1 estimated it at one-third of Fig. 167. 



the length; and Dumas 2 carried it still higher. 

 It must, of course, be proportionate to the 

 length of the fibres, being greater, the longer 

 the fibres. It has, also, been a subject of ex- 

 periment and speculation, whether the bulk 

 and the specific gravity of a muscle be aug- 

 mented during contraction. Borelli 3 and Sir 

 Anthony Carlisle 4 affirm, that its bulk is in- 

 creased. In the experiments of the latter, 

 the arm was immersed in a jar of water, with 

 which a barometrical tube was connected; and 

 when the muscles were made to contract 

 strongly, the level of the water in the tube 

 was raised. Glisson, however, from the same 

 experiment, deduced opposite conclusions; 

 Swammerdam and Ermann 5 appear to be of 

 their opinion; but Sir Gilbert Blane, 6 Mr. 

 Mayo, 7 Barzellotti, 8 MM. Dumas and PreVost, 9 

 and Valentin, 10 during the most careful ex- 

 periments could see no variation in the level 

 of the fluid; and, consequently, do not believe, 

 that the size of a muscle is modified by con- 

 traction. Sir Gilbert enclosed a living eel in Jj[ 

 a glass vessel filled with water, the neck of 

 which was drawn out into a fine tube; he then, by means of a wire 

 introduced into the vessel, irritated the tail of the animal, so as to ex- 

 cite strong contraction, during which he noticed, that the water in the 

 vessel remained stationary. He, likewise, compared the two sides of a 

 fish, one of which had been crimped, and thus brought into a state of 

 strong contraction; the other left in its natural condition: their specific 

 gravity was the same. The experiment of Barzellotti was the following. 

 He suspended, in a glass vessel, the posterior half of a frog; filled the 

 jar with water, and closed it with a stopper, traversed by a narrow, 

 graduated tube. The muscle was then made to contract by means of 

 galvanism, but in no case was the level of the liquid in the tube changed. 

 It may, then, be concluded, that the bulk of a muscle is not much, if 

 at all, greater when contracted than when relaxed. Professor E. Weber, 

 who repeated the experiments of Ermann, detected an increase of bulk, 

 but it was exceedingly small. 11 



1 Tentamina-Medico-Physica, Lond., 1718. 



2 Principes de Physiologie, &c., 2de edit., Paris, 1806. 



3 De Motu Animaliurn. addit. J. Bernouillii, Medit. Mathem. Muscul., L. B. 1710. 



4 Philos. Transact, for 1805, pp. 22, 23. * Gilbert's Annalen, p. 40, 1812. 



6 A Lecture on Muscular Motion, &c., Lond., 1778'; and Select Dissertations, &c., p. 239. 



7 Anatomical and Physiological Commentaries, i. 12; and Outlines of Human Physiology, 

 3d edit., p. 35, Lond., 1833. 



8 Esame di alcune moderne Teorie intorno alia Causa prossima della Contrazione mos- 

 colare, Siena, 1796. 9 Op. citat, and Magendie, Precis, &c., i. 222. 



10 Lehrbuch der Physiologie des Menschen, s. 42, Braunschweig, 1844; and Grundriss 

 der Physiologie, s. 218, Braunschweig, 1846. 



11 Art. Muskelbewegung, in Wagner's Handworterbuch der Physiologie, 15te Lieferung, s. 

 52 und 121, Braunschweig, 1846. 



