13. State the functions of the capillaries. Show how their structure
adapts them to their work.

14. What kind of physical exercise tends to strengthen the heart? What
forms of exercise tend to injure it? State the effects of alcohol and
tobacco on the heart.

15. How may rheumatism injure the heart?

16. Give directions for checking the flow of blood from small and from
large blood vessels.



PRACTICAL WORK


In showing the relations of the different parts of the heart, a large
dissectible model is of great service (Fig. 24). Indeed, where the time of
the class is limited, the practical work may be confined to the study of
the heart model, diagrams of the heart and the circulation, and a few
simple experiments. However, where the course is more extended, the
dissection of the heart of some animal as described below is strongly
advised.

*Observations on the Heart.*—Procure, by the assistance of a butcher, the
heart of a sheep, calf, or hog. To insure the specimen against mutilation,
the lungs and the diaphragm must be left attached to the heart. In
studying the different parts, good results will be obtained by observing
the following order: