808 JOHN BERRY HAYCRAFT. 
recognising the beaded appearance.1_ The beaded thread was the 
cause of some dispute, for the question arose, Was it a linear 
series of globules or a moniliform filament? and the final settle- 
ment of this must, indeed, have been a matter of great difficulty 
to those older savants, when we consider the imperfect lenses at 
their disposal. Krause and others maintained the former view, 
while Schwann held that which subsequent investigators have 
shown to be the correct one. The fibrille, according to Schwann, 
present a very regular succession of bead-like enlargements, 
darker than the very short constrictions which lie between. 
Thus, before the time of Bowman, the following important facts 
had been made out, namely, that the fibre is composed of a 
bundle of beaded fibrillee cemented together, and that the fibrille 
are cross striped, giving the whole fibre a like appearance of 
striation. Erroneous views had often, it is true, been advanced, 
but these had never received general acknowledgment. Mr. 
Skey (‘ Phil. Trans.’ of 1837), for instance, considered the fibres 
to be tubes filled with a soluble gluten, the strie surrounding 
and binding them together. Leeuwenhoek had a somewhat 
similar view of the construction of the cross strie, and Proch- 
aska considered them as depressions caused by the clasping of 
neighbouring capillaries and thready tissues. 
Mr. Bowman communicated to the Royal Society, in 1840, a 
paper “On the Structure and Movements of Voluntary Muscle,” 
in which he confirmed many of the opinions of his predeces- 
sors, adding, at the same time, much of what was fresh to our 
store of knowledge. He it was who first described the thin 
elastic membrane (sarcolemma) covering and ensheathing the 
fibres, showing how easily to demonstrate its existence, and giving 
figures of it, which have been copied into most modern histo- 
logical works. The nuclei of the sarcolemma he also figured, 
but what most concerns us is his description of the cross stria- 
tion. Mr. Bowman, I believe, first pointed out that not only can a 
fibre be split up longitudinally into fibrille along certain dark 
lines which may generally be seen, even in fresh preparations, 
but that it splits up transversely along the dark stripes. Hach 
fibrilla may, therefore, be split up into tiny segments across the 
dark strie. ‘‘On the whole, little doubt remains in my mind 
that the fibrillaee consist of a succession of solid segments or 
beads connected by intervals generally narrower, and I believe 
the beads to be light, and the intervals the dark spaces when the 
fibrilla is in exact focus.” His idea of a fibre naturally follows 
from that just given of a fibrilla, and, quoting again from him, 
1 Consult a drawing by Allen Thomson in illustration of Dr. Martin 
Barry’s paper on the “Structure of Muscular Fibrils,” ‘ Phil. Mag..,’ ser. 
4, vol. 6, plate v, fig. 2. 
