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QUARTERLY CHRONICLE. 57 
*‘ With regard to the arrangements of the contents of the 
sarcolemma—that is, the essential and characteristic element 
of the striped muscle—I may compare it to a ladder of con- 
tractile tissue, the steps or horizontal bars of the ladder being, 
however, spiral bands, whereas its side pieces or perpendi- 
cular supports are flat bands running continuously from one 
end of the muscle to the other end. The horizontal bars 
connect these perpendicular ones, but, as above stated, are 
curled upon themselves like a spiral spring. 
*< As to the contractile tissue, it appears to me to be a ho- 
mogeneous substance, its property being to contract in obe- 
dience to the nervous force set in motion either by a voluntary 
or a reflex stimulus. I believe the unstriped muscle affords 
us one of the least complicated examples of this contractile 
tissue to be found in the human subject, and I hold that the 
crystalline lens is equally muscle, and probably the most 
complex arrangement of contractile tissue to be met with. 
By this I mean that I have every reason to suppose the lens 
is capable of altering the curvature of its anterior surface in- 
dependently of the ciliary muscle. I conceive the bands of 
which it 1s composed are constructed of contractile tissue, 
arranged in a peculiar manner, that they may fulfil a special 
purpose ; but whatever form the contractile tissue may take, 
its properties are the same, the disposition of its elements 
being adapted to the mechanical purposes for which it is re- 
quired. Each primitive fibre of muscle, therefore, is formed 
of two parallel bands of this contractile tissue, which run 
continuously from one end of the muscle to the other end, 
and these parallel bands are united by cross bands, which, 
however, are continuous with the side bands, so that, to carry 
our simile a step further, we must liken this arrangement, 
not to an ordinary ladder—each step or bar being a separate 
piece of wood—but suppose that the ladder has been carved 
out of a svlid mass, the spaces between the bars having been 
scooped out of the plank from which we imagine the ladder 
to have been made. Lach one of these cross-bars or steps is 
arranged asa spiral band. Enclose the whole of this in a 
layer of sarcolemma, and we have a primitive fibre; take a 
bundle of these and bind them round in connective tissue, 
and we have a bundle of muscular fibre; and of a collection 
of these, again, the bulk of the muscle is composed. 
“The apparent object of this disposition of the contractile 
-element in muscular fibre is to allow of the contraction of the 
muscle in length without any great augmentation in its bulk, 
the spaces between the horizontal bars allowing of this, and 
