Written on the centenary of Finlay's birth, this biography is a sympathetic study of the man and a vigorous statement of the belief that Finlay was the real discoverer of the essential part played by the mosquito in the transmission of yellow fever. Not only does the author give credit to Finlay for originating the hypothesis, but he holds that there is abundant evidence that Finlay did actual experimental transmissions of the disease as early as 1881 by mosquitoes that were unquestionably Aedes aegypti. Considerable space is given to the elucidation of the exact accomplishments of the American commission headed by Dr. Walter Reed. The early works of Beauperthuy are extensively quoted and discussed, with the result that much of the glamor usually thrown around this writer is dispersed. This book will be of great value especially to students of tropical medicine and of medical history.