100 DR. MARTIN BARRY ON FIBRE. 



46. This flat filament is so situated in the fasciculus of voluntary muscle, as to pre- 

 sent its edge to the observer (fig. 62) ; the curves of only one of its two spirals being 

 seen. After removal, also, from the fasciculus, the filament very frequently lies, more 

 or less, upon its edge. It seems to have been the appearance presented by the edge 

 of this filament that is to say, by the curves of a spiral thread, that suggested to 

 SCHWANN the idea of longitudinal bead-like enlargements of the fibril, as producing 

 striae in the fasciculus of voluntary muscle. 



47. In my opinion, the dark longitudinal striae are spaces (probably occupied by a 

 lubricating fluid) between the edges of flat filaments, each filament being composed 

 of two spiral threads : and the dark transverse striae, rows of spaces between the 

 curves of these spiral threads. If the dark longitudinal striae are spaces between the 

 edges of flat filaments, it follows that the light longitudinal striae are the edges them- 

 selves of these filaments. And if the dark transverse striae are rows of spaces between 

 the curves of spiral threads, the light transverse striae are of course the visible por- 

 tions themselves of these spiral threads. 



48. I repeat, that the longitudinal filament in the fasciculus of muscle, appears to 

 be composed of two spiral threads, only one of which is seen, from the edge of the 

 filament being directed towards the observer. This filament, or its edge, seems to 

 correspond to the primitive marked thread of FONTANA ; to the primitive Jibre of VA- 

 LENTIN, and SCHWANN ; to the marked Jilament of SKEY; to the elementary Jibre of 

 MANDL ; to the beaded Jibril of SCHWANN, MULLER, LAUTH, and BOWMAN ; and to the 

 granular Jibre of GERBER. 



49. In the Philosophical Transactions for 1840 (p. 605), I suggested that, were the 

 nucleus of the blood-corpuscle the seat of changes such as I had witnessed and de- 

 scribed in other cells, the nucleus might produce the muscular fibril. The foregoing 

 observations show that the conjecture then offered has been realized : but, I must 

 add, in a most unexpected manner. 



50. The chief physiological inferences deducible from a spiral form of the finest 

 threads of muscle, will I think be obvious. At all events, it would be premature for 

 me to introduce remarks on this subject at any length, before my researches are con- 

 firmed by those of other observers. Yet there are two or three conclusions that 

 seem called for, in connection with the foregoing facts. 



51. Every one knows that in proportion as a spiral is shortened, the spaces between 

 the curves of the spiral are made smaller, and the diameter of the spiral expands : 

 while, in proportion as the spiral is lengthened, as by removing further asunder its 

 two ends, the spaces between the curves of the spiral are made greater, and the dia- 

 meter of the spiral is diminished. This may serve to illustrate what takes place in a 

 muscle ; which is no other than a vast bundle of spirals : showing that the muscle in 

 contraction should be short and thick ; while upon the other hand, in relaxation it 

 should be long and thin (compare a and (3 in fig. 66). 



