Another phase of the same condition is seen in Ecuador. Guayaquil, the port of Ecuador, is located on Guayas River at sea level, not more than three degrees from the equator. Here yellow fever always prevails, and the native of Guayaquil is not liable to the disease and never has it. Quito, the capital of Ecuador, is situated about two hundred miles away, right on the equator, and on the great Andean plateau ten thousand feet above sea level. The stegomyia cannot breed at Quito, so that yellow fever has never occurred there. The native of Quito, therefore, has no immunity to yellow fever, and of this he is well aware. Guayaquil is the only seaport of Ecuador, and everyone leaving the country has to leave through this port. Hundreds of the natives of Quito have died of yellow fever contracted by passing through Guayaquil. The man from Quito dreads Guayaquil a great deal more than did the American in the early days fear Panama. Dr. Reed, therefore, to make his experiments of any value, had to get human beings who had neither suffered from yellow fever itself, nor had lived long enough in an endemic center to acquire immunity. Havana for a number of years had received a considerable Spanish immigration. At the time to which I refer, it amounted to about twenty thousand a year. These immigrants believed that they were going to have yellow fever, and though they knew that a considerable number of them must succumb during the process, they were anxious to have the disease and be done with it. There was a very general belief among the Spaniards in Havana that a person with what they called “thin blood” as contra-distinguished from a robust, plethoric, full-blooded person, was much more likely to recover from yellow fever. They tried, therefore, with their newly arrived friends, relatives and dependents from Spain to bring about this condition of their blood. They kept them confined in a darkened room and fed them on a very limited diet, and certainly succeeded in rapidly reducing the strong, florid, robust Gallego to a very marked condition of anemia and debility. The Spaniard believed that he thus saved many lives. I was convinced that he thus killed a good many of his friends and dependents. The newly arrived Spaniard, as soon as he had had yellow fever and could present a certificate of immunity, could command double the wages that he could get before he had the disease. So that when Dr. Reed proposed to some of these men that they should go out to his camp, have a mild case of yellow fever, be well cared for and when recovered be given by him a certificate of immunity, he found no difficulty in getting volunteers, and when, in addition to that, he promised each man who had the disease a bonus of two hundred and fifty dollars, the service became exceedingly popular.