In our series we have encountered no cases of pericarditis. This lesion in the experience of others has also been unusual, and it would appear that bacterial invasion of this sac is accomplished mainly in the presence of secondary infections localizing in the neighboring pleura. It was not uncommon to find a slight increase in the serous fluid in the sac, but this on no occasion amounted to a hydropericardium. The fluid was always clear and with no evidence of fibrin or cellular exudate. Petechial hemorrhages scattered over the epicardium were noted in seven cases. In the majority of instances these minute hemorrhages were scattered in small numbers over the ventricular walls. In one instance these petechial hemorrhages were also present through the myocardium, suggesting the influence of an intoxication not upon the tissues of the heart as much as upon the finer structures of the vascular channels. This is furthermore borne out in the presence of petechial hemorrhages confined not to one organ, but to various tissues and structures in the body. More or less cloudy swelling or granular degeneration of the muscle elements of the heart was not uncommon. It was sufficiently pronounced in 12 cases to be readily detected by the naked eye. A lesser amount was also observed in other cases on microscopical examination. In only one instances was the myocardial degeneration of such extent to lead to a definite and recognizable weakening of the musculature. In this instance the autopsy showed a flabby myocardium which was relatively soft and easily broken and in which all the chambers of the heart were decidedly dilated. This was the only case in which we were convinced of a sufficient influence of the toxic effects upon the musculature to permit a stretching of the walls, with failure of function. In a number of other instances, however, in which there was more or less granular degeneration and cloudy swelling we found that the right ventricle ceased in diastole without, however, the capacity of the chamber being enlarged. We would make this differentiation in speaking of dilatation of the heart. We have met with 11 cases in which the right heart died in diastole, but in which there was no evidence that the right ventricle had been unduly expanded. In four cases there was evidence of an old compensatory hypertrophy of the left ventricle in which the cavity of this chamber was also slightly larger than normal. The lesions in these four cases, however, bore no direct relation to the results from the influenza infection. The appearance of the musculature with moderate grade of cloudy swelling suggested some œdema of the tissues. In the myocardium, œdema is difficult to recognize, and we would not place great stress upon its presence in mild degree.