ch these direful results frequently invade the
system, and the easily moulded condition of youth yields readily to the
destructive snare.

"The first effect of a cigar upon any one demonstrates that tobacco can
poison by its smoke and through the lungs."--London _Lancet_.

"The action of the heart and lungs is impaired by the influence of the
narcotic on the nervous system, but a morbid state of the larynx, trachea,
and lungs results from the direct action of the smoke."--Dr. Laycock,
Professor of Medicine in the University of Edinburgh.

Additional Experiments.

Experiment 114. _To illustrate the arrangement of the lungs and the
two pleurae._ Place a large sponge which will represent the lungs in a
thin paper bag which just fits it; this will represent the pulmonary
layer of the pleura. Place the sponge and paper bag inside a second
paper bag, which will represent the parietal layer of the pleura. Join
the mouths of the two bags. The two surfaces of the bags which are now
in contact will represent the two moistened surfaces of the pleurae,
which rub together in breathing.

Experiment 115. _To show how the lungs may be filled with air._
Take one of the lungs saved from Experiment 110. Tie a glass tube six
inches long into the larynx. Attach a piece of rubber to one end of the
glass tube. Now inflate the lung several times, and let it collapse.
When distended, examine every part of it.

Experiment 116. _To take your own bodily temperature or that of a
friend._ If you cannot obtain the use of a physician's clinical
thermometer, unfasten one of the little thermometers found on so many
calendars and advertising sheets. Hold it for five minutes under the
tongue with the lips closed. Read it while in position or the instant it
is removed. The natural temperature of the mouth is about 98-1/2 degrees
F.

Experiment 117. _To show the vocal cords._ Get a pig's windpipe in
perfect order, from the butcher, to show the vocal cords. Once secured,
it can be kept for an indefinite time in glycerine and water or dilute
alcohol.

Experiment 118. _To show that the air we expire is warm._ Breathe
on a thermometer for a few minutes. The mercury will rise rapidly.

Experiment 119. _To show that expired air is moist_. Breathe on a
mirror, or a knife blade, or any polished metallic surface, and note the
deposit of moisture.

Experiment 120. _To show that the expired ai