doubt of the improvement in practice. Most important also has been the growth of our knowledge of the transmission of disease especially the part played therein by carriers. The crowning triumph in this field is the complete elucidation of the mode of transmission of Bilharzia, a disease with which we were faced through the presence of large contingents of our troops in Lower Egypt. It is a disease which is present in a chronic form in some three fourths of the male population of Lower Egypt, has existed there since the days of the Pharaohs and extends from the South of Africa to Mesopotamia on the one hand and the West Indies on the other. We have obtained full knowledge of its mode of transmission and its life conditions and they are such as point the way to effective action in the direction of its extirpation. If we succeed in checking its spread it will be indirectly due to the strain of the war which makes us alive to the necessity for prompt action and creates not merely a willingness but an eagerness to accept all the aid that Science can 56
