20. What forces besides that of the heart aid in propelling the blood?
21. Why can the pulse be best felt in the wrist? 22. Why are starving people exceedingly sensitive to any jar?
23. Why will friction, an application of horse-radish leaves, or a blister relieve internal congestion?
24. Why are students very liable to cold feet?
25. Is the proverb that "blood is thicker than water" literally true?
26. What is the effect upon the circulation of "holding the breath"?
27. Which side of the heart is the stronger?
28. How is the heart itself nourished? [Footnote: The coronary artery, springing from the aorta just after its origin, carries blood to the muscular walls of the heart; the venous blood comes back through the coronary veins, and empties directly into the right auricle.]
29. Does any venous blood reach the heart without coming through the venæ cavæ?
30. What would you do, in the absence of a surgeon, in the case of a severe wound? (See p. 258.)