sh muscle found in a piece of beef is a good example of striated
muscle. The clear ring surrounding the intestine of a cat (shown by cross
section) and the outer portion of the preparation from the cow's stomach,
sold at the butcher shop under the name of _tripe_, are good examples of
non-striated muscular tissue. The heart of any animal, of course, shows
the heart muscle.

*To show the Structure of Striated Muscle.*--Boil a tough piece of beef, as
a cut from the neck, until the connective tissue has thoroughly softened.
Then with some pointed instrument, separate the main piece into its fiber
bundles and these in turn into their smallest divisions. The smallest
divisions obtainable are the muscle cells or fibers.

*To show Striated Fibers.*--Place a small muscle from the leg of a frog in
a fifty-per-cent solution of alcohol and leave it there for half a day or
longer. Then cover with water on a glass slide, and with a couple of fine
needles tease out the small muscle threads. Protect with a cover glass and
examine with a microscope, first with a low and then with a high power.
The striations, sarcolemma, and sometimes the nuclei and nerve plates, may
be distinguished in such a preparation.

*To show Non-striated Cells.*--Place a clean section of the small intestine
of a cat in a mixture of one part of nitric acid and four parts of water
and leave for four or five hours. Thoroughly wash out the acid with water
and separate the muscular layer from the mucous membrane. Cover a small
portion of the muscle with water on a glass slide and tease out, with
needles, until it is as finely divided as possible. Examine with a
microscope, first with a low and then with a high power. The cells appear
as very fine, spindle-shaped bodies.

*To illustrate Muscular Stimulus and Contraction.*--Separate the muscles at
the back of the thigh of a frog which has just been killed and draw the
large sciatic nerve to the surface. Cut this as high up as possible and,
with a sharp knife and a small pair of scissors, dissect it out to the
knee. Now cut out entirely the large muscle of the calf of the leg (the
gastrocnemius), but leave attached to it the nerve, the lower tendon, and
the bones of the knee. Mount on an upright support, as shown in Fig. 120,
and fasten the tendon to a lever below by a thread or small wire hook:

[Fig. 120]

Fig. 120--*Apparatus* for demonstrating properties of muscles.