194 
HISTOLOGY OF ANIMALS. 
muscle consists of a series of fibres, each of which 
is termed a fasciculus, and each fasciculus is invested by 
a sheath of structureless membrane, termed the sar- 
colemma (Fig. 147, b). The muscle itself is surrounded 
, , _ by areolar tissue, which dips 
FIG. 146 . J 1 
in among the fasciculi, and 
gives support to the blood- 
vessels and nerves. If a muscle 
be injected, the capillaries, as 
represented in Fig. 146, are 
readily seen ; they rim in 
parallel lines between the fas- 
ciculi, and transverse connect- 
ing branches are given off 
at tolerably regular distances. 
The fasciculi exhibit transverse and longitudinal stride, 
but, in most cases, the former, as shown in Fig. 147, A, 
are more plainly exhibited than the latter. In some 
animals the fasciculi break up transversely, in others 
longitudinally, so that, in the one case, we have a series 
of discs, and in the other numerous filaments termed 
fibrillae. The fasciculi of the Eel readily break up 
into discs, whilst those of man and most mammalia 
commonly separate into fibrillae. If the flat surfaces 
of the discs, at F, in Fig. 147, be examined, they 
present a granular aspect, which is due to their being 
made up of the ends of the fibrillae ; and, if the fibrillae 
be viewed with a power of five hundred diameters each 
one, as shown at b, will exhibit a beaded structure, the 
FIG. 146 . 
Capillaries of voluntary 
muscle. 
