488 
MR. BOWMAN ON THE MINUTE STRUCTURE AND 
approximation of the bead-like enlargement can neither be demonstrated nor proved 
not to take place, but he seems inclined to think such a conjecture not improbable, 
because the beads of the fibrillee are not necessary to the contraction of the fasciculus 
into belly-like portions, or to their zigzag inflexion ; and also because the striae are not 
always at the same distance on contiguous fasciculi. “This,” he adds, “is all that 
can be said in support of the hypothesis of the approximation of the globular enlarge- 
ments of the primitive fibrillee*.” 
I was endeavouring eighteen months ago to inspect, under the microscope, a fasci- 
culus of a Frog, excited by galvanism, and had induced contractions in the specimen 
so often that it seemed no longer to obey the stimulus applied to it. Continuing to 
regard it, however, I was surprised to perceive a spontaneous and slow movement, 
which consisted of an approximation of the transverse strise, with a corresponding- 
shortening and thickening of the fasciculus. What I have now to offer is chiefly 
embodied in this simple fact, though Somewhat amplified by subsequent researches. 
From these I am enabled to say with confidence, that in that form of contraction 
which takes place as the last act of vitality, the transverse strise, that is, the discs of 
the fasciculus, approach each other, become thinner, and expand in circumference ; in 
other words, the contractility of muscle is independent of any inflexions of its fas- 
ciculi, and resides in the individual segments of which these are composed. I have 
taken from the animal, immediately after death, a minute piece of some muscle, ge- 
nerally of the extremities, and laid it upon glass, then quickly tearing it into many 
fragments with needles, so as to separate the fasciculi as much as possible from one 
another, have moistened it with water, and covered it with a lamina of mica : a mag- 
nifying power of 300 or 400 diameters has then been employed. In this manner the 
muscle of animals possessing transverse strise may be seen in a contracting state. 
The contraction commences usually at the cut extremities of the fasciculi (fig. 85.), 
which are thereby rendered more opake. The strise are here seen to be two, three, 
or even four times as numerous as in the intermediate part, and also proportionally 
narrower and more delicate. As the process goes on, the strise advance towards 
those of the contracted portion, and on approaching it are gradually ranged in close 
apposition to them. The line of demarcation between the contracted and uncon- 
tracted portions is well defined, and as fresh strise are absorbed from the latter into 
the former, it is seen to make an onward progress. As it advances upon the uncon- 
tracted portion, this diminishes rapidly in length, without the contracted part experi- 
encing an equivalent elongation ; the consequence of which is a shortening of the 
whole fasciculus. The contracted part augments in thickness, but in a degree, I 
think, incommensurate with its diminished length, so that its solid parts actually lie 
in smaller compass than before ; they are brought into closer apposition with one an- 
other. The effect of this is, that the water that has been absorbed is pressed out 
from the fibrillee, and accumulates, where it is best able to do so, between the fibrillee 
* Physiology, Baly’s Translation, p. 889-90. 
