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. 
4/. 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 fibre of Va- 
lentin, and Schwann ; to the marked filament of Skey ; to the elementary fibre of 
Mandl ; to the beaded fibril of Schwann, Muller, Lauth, and Bowman ; and to the 
granular fibre 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). 
