s, rigidly prohibit the use of tobacco by their pupils. So also
young men in athletic training are strictly forbidden to use it.[12] This
loss of muscular vigor is shown by the unsteady condition of the muscles,
the trembling hand, and the inability to do with precision and accuracy
any fine work, as in drawing or nice penmanship.

Additional Experiments.

Experiment 23. _ To examine the minute structure of voluntary
muscular fiber._ Tease, with two needles set in small handles, a bit of
raw, lean meat, on a slip of glass, in a little water. Continue until
the pieces are almost invisible to the naked eye.

Experiment 24. Place a clean, dry cover-glass of about the width of
the slip, over the water containing the torn fragments. Absorb the
excess of moisture at the edge of the cover, by pressing a bit of
blotting-paper against it for a moment. Place it on the stage of a
microscope and examine with highest obtainable power, by light reflected
upward from the mirror beneath the stage. Note the apparent size of the
finest fibers; the striation of the fibers, or their markings,
consisting of alternate dim and bright cross bands. Note the arrangement
of the fibers in bundles, each thread running parallel with its
neighbor.

Experiment 25. _To examine the minute structure of involuntary
muscular fiber, a tendon, or a ligament._ Obtain a very small portion of
the muscular coat of a cow's or a pig's stomach. Put it to soak in a
solution of one dram of bichromate of potash in a pint of water. Take
out a morsel on the slip of glass, and tease as directed for the
voluntary muscle. Examine with a high power of the microscope and note:
(1) the isolated cells, long and spindle-shaped, that they are much
flattened; (2) the arrangement of the cells, or fibers, in sheets, or
layers, from the torn ends of which they project like palisades.

Experiment 26. Tease out a small portion of the tendon or ligament
in water, and examine with a glass of high power. Note the large fibers
in the ligament, which branch and interlace.

Experiment 27. With the head slightly bent forwards, grasp between
the fingers of the right hand the edge of the left
sterno-cleido-mastoid, just above the collar bone. Raise the head and
turn it from left to right, and the action of this important muscle is
readily seen and felt. In some persons it stands out in bold relief.

Experiment 28. The t