142 ANATOMY OF THE MUSCULAR FIBRE. 



nearer eacli other, and, in consequence, the whole fibre 

 becomes shorter and broader, and its extremities are 

 caused to approximate, and thus mechanical pulling 

 work may be done. At the same time, a little of the 

 fluid contained amongst the fibrillse is forced out, forms 

 vacuoles (Kiihne), and lies in bullse, or blebs, beneath 

 the sarcolemma, which is drawn up into wrinkles 

 (Carpenter). This last circumstance, and the fact that 

 this membrane is always very delicate, and, in some 

 muscles (even the strongest, as the heart) entirely 

 wanting, may let us at once put it out of account in 

 the mechanical agency. 



The question is, as Briicke states it, " How can a solid sub- 

 stance, even of the consistence merely of a trembling jelly, 

 really set about the process of contracting itself ' also, whence 

 is derived the force to do that work 1 ? Kuhne* agrees with 

 Bowman, and others, that a wave-like swelling passes along the 

 fibre during contraction when touched, which he thinks shows 

 a state almost of fluidity ; and, in opposition to Kolliker, he 

 says it would be unduly stretching the definition of a solid to 

 call the fibre solid, for it possesses the perfect mobility of the 

 molecules of a fluid, and, in consequence, takes the form which 

 would be given by gravity, therefore it remains after the con- 

 tracting force is withdrawn pretty much as it would under 

 gravity, and in a state not very different from the contracted 

 shape, unless drawn out by the elasticity or the weight of 

 neighbouring parts. He will not admit the propriety of speak- 

 ing-of a semi-fluid, but says the muscular fibre is a closed tube 

 containing fluid and the muscle prisms. This Beale will not 

 admit, but contends for the state of a soft solid, because some 

 fibres, viz., those of the heart, are destitute of sarcolemma. 

 The action of the flesh-prisms, or sarcous particles, is also very 

 difficult to understand. Briicke (Strieker, Syd. Soc., i.) shows 



* Reichert and Duboia' " Archiv," 1859, p. 809. 



