"Time will not permit--what to you is probably quite unnecessary--the recapitulation of the story of the labours of Reed and his coadjutors. I cannot pass on, however, to what I have to say in connection with this work without a word of admiration for the insight, the energy, the skill, the courage, and withal the modesty and simplicity of the leader of that remarkable band of workers. If any man deserved a monument to his memory, it was Reed. If any band of men deserve recognition at the hands of their countrymen, it is Reed's colleagues. "The principal outcome of the labours of these men has been the demonstration, first, that the ultra-microscopic germ of yellow fever is present in the blood of the patient during the first three days of the disease. Second, that the first step in the passage of the germ from the sick to the sound is made, under natural conditions, in the stegomyia mosquito. And third, that after about twelve days and upwards in stegomyia, the yellow fever germ, when implanted by the said mosquito into another human host, is capable of reproduction, so that at the end of a further period of about three days it has established itself throughout the blood, is causing the violent reaction, the clinical manifestations of which we call yellow fever, and is once more in a condition to re-enter the mosquito. "These are great etiological facts. They are of supreme practical and scientific value. Acting on them, the United States sanitary authorities expelled yellow fever from Havana. Acting on them, they should be able in the future to protect the United States themselves from such terrible visitations as in the past have swept through some of your cities." 3. FILARIASIS These same lectures contain an admirable account of the life-history of _Filaria_. It is not necessary here to describe the loathsome deformities which occur in the later stages of filariasis. These deformities (_elephantiasis_, Barbadoes leg), which may attain colossal size, are due to the blocking of the lymphatic vessels with filarial worms. Cases of the disease are hardly ever seen in this country; but it is very frequent in some parts of the tropics. _In the endemic areas_, says Manson, _10 per cent. is not an uncommon proportion of the population to be found affected with filariasis. Thirty and even 50 per cent. may be affected. In many of the Pacific Islands--the Samoa group for instance--I believe that even this proportion is exceeded._