CAUSE OF STRIATION OF VOLUNTARY MUSCULAR TISSUE. 309 
we find “a fibre consists of sarcous elements (so he termed the 
little segments or beads) arranged and united together endways 
and sideways, so as to constitute in these directions respectively 
fibrillee and discs, either of which may in certain cases be 
detached as such,” and “‘ the dark longitudinal striz are shadows 
between fibrille, the dark transverse strie shadows between 
discs.” 
It will be seen that in one particular Bowman disagreed with 
Schwann and the older writers, and at the same time with those 
of more recent date. According to him, the bead was light and 
the constriction dark, when the muscle was in exact focus, a 
description at variance with everyone. In the same paper he 
mentions this remarkable fact, that on altering the focus the 
stripes were reversed ; he must have examined it—this bears in 
a most important way on our investigations, to be afterwards 
described—in the reverse focus of what it is ordinarily figured 
in. His view of the form, and the splitting of the fibre, was 
probably correct, for he described the cleavage as occurring in 
the narrow part, which appeared to him, focussing as he did, to 
be dark, and indeed it is often difficult to say which it is, 
whether dark or light, for, as we shall more particularly mention 
afterwards, the slightest alteration of the focus is sufficient to 
reverse the appearance of the fibre. Bowman, moreover, ac- 
counted for these light and dark parts of the fibrille, comparing 
a muscular filament to a glass rod with alternate swellings and 
depressions, which, when viewed with transmitted light, gives 
just the same appearance, and from a study of his paper, although 
it is here somewhat indefinite, I judge that he concluded the 
moniliform shape to be a cause of the striping.! 
Now, this last-named and important discovery of Bowman’s 
has, I believe, completely been lost sight of, for no mention of 
it can be found in any modern monograph nor in any systematic 
text-book that I have examined. ‘The striking points in the 
paper and in the figures he gives, is the splitting up of the fibre 
into transverse discs and the demonstration of the sarcous 
elements as before quoted. This, together with the sarcolemma, 
every one connects with the name of Bowman. Modern inves- 
tigators have worked mostly at the cross striping of muscle, 
and have found it more complicated than Bowman described, 
owing, no doubt, to the use of better glasses; while he ex- 
plained the phenomenon as due simply to the shape of the 
fibres—believing, however, probably that it was due also to 
1 Bowman, nevertheless, seems to consider the dark stripe of a different 
structure from the light, not so much from the shading, but from the 
transverse cleavage. He is not quite definite here, but this is the impres- 
sion I have gained from a careful perusal of his paper. 
