“The serious respiratory infections of the bronchi and lungs we can set down with reasonable certainty as complications due, certainly in the overwhelming majority of cases, to secondary bacterial invaders. It is a matter of considerable difficulty, however, to know exactly where the basic disease stops and the complications begin; and whether we must regard the mild sore throat and conjunctival injection which so often accompany the simple cases as a part of this basic clinical picture, or as the simplest variety of complication. This is much more than an academic question, since, as we shall see, the bacteriological analyses of such lesions have played an important role in etiological investigations.” SYMPTOMS IN FORMER EPIDEMICS. The difficulty in making a decision in the presence of an epidemic is very similar to that of deciding whether the epidemics of former times were in each case influenza. Some few have been recorded in which the description has corresponded fairly well to that of primary uncomplicated influenza. Thus, concerning the epidemic of 1557 in Spain, Thomas Short wrote as follows: “At Mantua Carpentaria, three miles from Madrid, the epidemic began in August.... There it began with a roughness of the jaws, small cough, then a strong fever with a pain of the head, back, and legs. Some felt as though they were corded over the breast and had a weight at the stomach, all of which continued to the third day at furthest. Then the fever went off, with a sweat or bleeding at the nose. In some few, it turned to a pleurisy or fatal peripneumony.” Most of the descriptions, however, have been of a general character and include descriptions of the complicated periods of the epidemic. One of the more complete of the early descriptions was that by Lobineau in 1414, who wrote: “C’était une espèce de rhume, qui causa un tel enrouement que les chastelets furent obligez d’interrompre leurs séances; on dormoit peu et l’on souffroit de grandes douleurs à la teste, aux reins et par tout le reste du corps; mais le mal ne fut mortel que pour les vieilles gens de toute condition.”