uricle.

4. How does the movement of air into and from the lungs differ from that
of the blood through the lungs with respect to (_a_) the direction of the
motion. (_b_) the causes of the motion, and (_c_) the tubes through which
the motion takes place?

5. How are the air passages kept clean and open?

6. Describe the pleura. Into what divisions does it separate the thoracic
cavity?

7. Describe and name uses of the diaphragm.

8. If 30 cubic inches of air are passed into the lungs at each inspiration
and .05 of this is retained as oxygen, calculate the number of cubic feet
of oxygen consumed each day, if the number of inspirations be 18 per
minute.

9. Find the _weight_ of a day's supply of oxygen, as found in the above
problem, allowing 1.3 ounces as the weight of a cubic foot.

10. Make a study of the hygienic ventilation of the schoolroom.

11. Give advantages of full breathing over shallow breathing.

12. How may a flat chest and round shoulders be a cause of consumption?
How may these deformities be corrected?

13. Give general directions for applying artificial respiration.

PRACTICAL WORK

Examine a dissectible model of the chest and its contents (Fig. 49). Note
the relative size of the two lungs and their position with reference to
the heart and diaphragm. Compare the side to side and vertical diameters
of the cavity. Trace the air tubes from the trachea to their smallest
divisions.

*Observation of Lungs* (Optional).--Secure from a butcher the lungs of a
sheep, calf, or hog. The windpipe and heart should be left attached and
the specimen kept in a moist condition until used. Demonstrate the
trachea, bronchi, and the bronchial tubes, and the general arrangement of
pulmonary arteries and veins. Examine the pleura and show lightness of
lung tissue by floating a piece on water.

*To show the Changes that Air undergoes in the Lungs.*--1. Fill a quart jar
even full of water. Place a piece of cardboard over its mouth and invert,
without spilling, in a pan of water. Inserting a tube under the jar, blow
into it air that has been held as long as possible in the lungs. When
filled with air, remove the jar from the pan, keeping the top well
covered. Slipping the cover slightly to one side, insert a burning
splinter and observe that the flame is extinguished. This proves the
absence of sufficient oxygen to support combustion. Pour in a little
limewater(43) and shake to mix with the air. The change o