Who is Dr. Alexander H. Macklin and Dr. James A. McIlroy, surgeons from Endurance: Shackleton's Incredible Voyage and what is their importance?

Alexander Macklin and James McIlroy are the two surgeons of the expedition. Macklin is an English doctor, born in India, and is highly educated. Aside from his surgeon's duties he is placed in charge of a team of sledge dogs. Macklin therefore spends considerable time on salvage and hunting expeditions subsequent to Endurance's destruction. Macklin is fond of his dogs and regrets their eventual execution and consumption, but knows the necessity of such an action. Macklin demonstrates a quick temper on a few occasions but is generally reliable and well-liked by his crewmates.