ORGANIZATION. 39 
we find it is made up of a number of fasciculz, or bundles 
of fibres, placed side by side, and bound together by con- 
nective tissue. The mi- 
croscope informs us that 
each fibre is itself a bun- 
dle of smaller fibres; and 
when one of these is 
more closely examined, 
it is found to be inclosed 
in a delicate, glossy tube, 
called the sarcolemma. 
This tube is filled with 
very minute, parallel 
+] Seo ae 1 
fibrils, averaging 5307 
‘ 5 5 Fia. 10.—Striated Muscular Fibre (of the Pig), 
of an inch in diameter, x 200. The constituent cells are seen at a; 
and having a beaded as- cis a fasciculus, or bundle. 
pect, each fibril being a row of cells. Tissue of this descrip- 
tion constitutes all ordinary muscle, or “lean 
meat,” and is marked by regular cross-lines, 
or stri@. 
Besides this striated muscular tissue, there 
exist, in the coats of the stomach, blood-ves- 
sels, and some other parts of Vertebrates, 
smooth muscular fibres, or membranes, which 
show a nucleus under the microscope, and 
do not break up into fibrils. The gizzards 
of fowls exhibit this form. 
All muscle has the property of shorten- 
ing itself when excited; but the contraction 
of the striated kind is under the control of 
the will, while the movement of the smooth 
Oe rata ines fibres is involuntary.” Muscles are well sup- 
fromtheheartof ylied with arteries,veins, and nerves ; but the 
Man, divided by 
transverse septa olor is due toa peculiar pigment, not to the 
into separate nu- 
cleated portions. blood. 
