45. INJURIES TO THE BLOOD-VESSELS.--It is important to be able to discriminate between an artery and a vein, in the case of a wound, and if we remember the physiology of the circulation we may readily do so. For, as we have already seen, hæmorrhage from an artery is much more dangerous than that from a vein. The latter tends to cease spontaneously after a short time. The arterial blood flows away from the heart with considerable force, in jets; its color being bright scarlet. The venous blood flows toward the heart from that side of the wound furthest from the heart; its stream being continuous and sluggish; its color dark. In an injury to an artery, pressure should be made between the heart and the wound; and in the case of a vein that persistently bleeds, it should be made upon the vessel beyond its point of injury. {122} QUESTIONS FOR TOPICAL REVIEW. PAGE 1. In what organisms is the so-called circulatory fluid found? 101 2. How is it designated in the different organisms? 101 3. What can you state of the importance of blood to the body? 101, 105 4. Of its great abundance, color, and composition? 101, 102, 107 5. Describe the corpuscles of the human blood. 102, 103, 104 6. What is said of them in comparison with those of the lower animals? 103 7. Of the importance of sometimes detecting human from other blood? 103 8. What means have we of detecting blood in spots or stains? 103, 104 9. What is meant by coagulation of the blood? 104 10. What wisdom is there in the law of the blood's coagulation? 104, 105 11. How is this wisdom made manifest? 105 12. In what cases is the aid of the surgeon required? 105 13. What are the two great uses of the blood? 105 14. Through what mediums is the blood provided with new material and relieved of the old material? 105 15. What do you understand by the operation called transfusion? 106 16. What cases of transfusion are reported of the lower animals? 106 17. What can you state of transfusion as practised upon man? 106 18. What further can you say on the subject? 106, 107 19. What changes take place in the color of the blood in its journey through the system? 107 20. State all you can in relation to the circulation of the blood. 107 21. All, in relation to the size, shape, and location of the heart. 107, 109 22. How is the loss of power in the heart movements obviated? 109 23. Give a description of the formation of the heart. 109, 110, 111 24.