We have been discussing the disease under consideration chiefly from the viewpoint of the statistician. The statistician, possessing a wealth of information of a general nature, and from all parts of the world, and armed with fascinating complex mathematical instruments, is able to dissect the information at his disposal, and to reconstruct therefrom both facts and apparent facts of absorbing interest. To him we are indebted for the bulk of our knowledge of the distribution and spread of the influenza through metropolises, through countries, and through continents. Like the aviator flying over enemy territory he acquires a breadth of vision and a general perspective which is to a great extent denied to those remaining on the ground. But also like the aviator, from the very fact of his high position he loses the ability to recognize detail. The small subdivisions in the enemy lines are slightly blurred and he can distinguish the front line trenches in which most of the action is occurring no more clearly than the reserve and support trenches. An Army depending entirely upon its aeroplane reconaissance would find itself helpless in combating the enemy. The aeroplane is useful, yes, it could not be dispensed with, but never an opportunity is lost for scouting parties to explore the enemy front lines; it is these latter who bring back information as to the local strength and distribution of the enemy, as to what particular divisions are in action, as to the strength of the entrenchments, the enemy distribution within the trenches, and finally what is most important, information as to the weak points in the enemy’s lines, places at which we may concentrate our attack with the hope of driving the enemy from its stronghold. Occasionally a raiding party will return with a prisoner. He will be examined thoroughly and may yield some valuable information. All such prisoners are not dressed alike. We recognize that some belong to one regiment and some to another. After we have extracted what information we can from the prisoner he is incarcerated, if we may extend our metaphor, in a test tube, and there he remains for future reference. We do not believe that these individual private soldiers are the cause of the war, but we do know that they are doing their share of the killing—that they are doing most of the killing.