368 MUSCULAR MOTION. 



that, on the contrary, violence causes a separation along the transverse 

 dark lines, which always intersect the fibre in a plane perpendicular to 

 its axis. By such a cleavage, disks and not fibrillse are obtained; and 

 this cleavage is as material as, although less frequent than, the former. 

 Hence, he esteems it as proper to say, that the fibre is a pile of disks, 

 as that it is a bundle of fibrillae; that it is, in fact, neither one nor the 

 other; but a mass in the structure of which there is an intimation of 

 the existence of both, and a tendency to cleave in the two directions. 

 If there were a general disintegration along all the lines in both direc- 

 tions, there would result a series of particles, which might be termed 

 primitive particles or sarcous elements, the union of which would con- 

 stitute the mass of the fibre; these elementary particles being arranged 

 and united together in the two directions. 



Gerber 1 is disposed to consider, that the "cross-streaking" fre- 

 quently depends on the presence of a wrinkled fascicular sheath; 

 "for when," he says, "the more superficial fibres chance to be removed, 

 and the deeper ones exposed, these appear cylindrical, and the bundle 

 at the part is longitudinally streaked. At the extremity of a torn fas- 

 ciculus, too, the peripheral fibres often appear so distinctly marked off 

 from the internal and more pulpy substance, that the existence of a 

 more compact transversely streaked sheath can scarcely be called in 

 question." Dr. Goddard 2 is of opinion, from his own observations, that 

 the transverse striae seem to be produced by a delicate thread of areolar 

 tissue wound spirally around the ultimate fibrils, so as to hold them in a 

 bundle ; whilst Dr. Will 3 thinks that they are owing to the fibrils, which, 

 in their natural relaxed state, are uniform and cylindrical, being thrown 

 in contraction into undulations or zigzag flexures ; and Valentin, 4 who has 

 long described the relaxed muscular fibre as a uniform cylinder, con- 

 firms, generally, Dr. Will's account, although he cannot determine, 

 whether the striated appearance of the fibrils be owing to their becoming 

 varicose, or to zigzag flexures induced by contraction. He also main- 

 tains the view, long professed by him, that the fibres and fasciculi in 

 the fully contracted state, are bent in zigzag lines, with angles of from 

 80 to 120. The zigzag arrangement of fibres having the appear- 

 ance of "series of rhomboidal pinnulse, which immediately disappear 

 as soon as the muscle ceases to act," was observed by Hales, 5 in the 

 abdominal muscles of the frog. 



Mr. Erasmus Wilson, 6 by resorting to peculiar methods of manipu- 

 lation, and employing a microscope of more than ordinary power, 

 believes that he has succeeded in discovering the real structure of the 

 ultimate muscular fibril in a specimen taken from the arm of a strong 

 healthy man immediately after amputation. He finds each fibril to be 

 composed of minute cells disposed in a linear series, flattened at their 

 surfaces of apposition, and so compressed in the longitudinal direction 



1 Elements of General and Minute Anatomy, by Gulliver, p. 251. 



2 Wilson's Anatomist's Vade Mecum, by Goddard, Amer. edit., p. 142, Philad., 1843. 



3 Mullet's Archiv., 1843, Heft iv. 



4 Lehrbuch der Physiologic des Menschen, ii. 33, Braunschweig, 1844. 



5 Statical Essays, ii. 61, Lond., 1733. 



Proceedings of the Royal Society, June 20, 1844. 



