79.  Effect of Tobacco on the Muscles.  That other prominent narcotic, tobacco, impairs the energy of the muscles somewhat as alcohol does, by its paralyzing effect upon the nervous system.  As all muscular action depends on the integrity of the nervous system, whatever lays its deadening hand upon that, saps the vigor and growth of the entire frame, dwarfs the body, and retards mental development.  This applies especially to the young, in the growing age between twelve or fourteen and twenty, the very time when the healthy body is being well knit and compacted.

Hence many public schools, as well as our national naval and military academies, 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.