Not all heroes are to be found in the army. Not all heroes are to be found in the army. Actully , many of them have been found in almost every field.
Early this century, a group of physicians were trying to discover the cause of the disease called yellow fever. At that time it was one of the worst disease known. Thousands of people were dying of yellow fever every year. It had been suggested that the disease was caused by the bite of a certain mosquito would bite a person who was ill with yellow fever and then, flying elsewhere, bite another person and give him the disease.
To prove whether or not this was true, one of the physicians,Dr James Carrol allowed such a mosquito to bite himself after it had bitten a patient with yellow fever. He knew that the bite of this mosquito might cause his death.