Weakness of the third phase, as a rule, indicates weakness of the heart and this dulling of the third phase may be so excessive that no sound is produced. Goodman and Howell have carried this method further by measuring the individual phases and calculating the percentage of each phase to the pulse pressure. Thus, if in a normal individual the systolic pressure is 130 mm., the diastolic 85 mm., and the pulse pressure 45 mm., the first phase lasts from 130 to 116 or 14 mm., the second from 116 to 96, or 20 mm., the third from 96 to 91 or 5 mm., the fourth from 91 to 85, or 6 mm. The first phase would then be 31.1 per cent of the total pulse pressure, the second phase 44.4 per cent, the third phase 11.1 per cent, and the fourth phase 13.3 per cent. They consider that the second and third phases represent cardiac strength (C. S.) and the first and fourth represent cardiac weakness (C. W.). They believe that C. S. should normally be greater than C. W. In the example above C. S.:C. W. = 55.5:44.4. In weak hearts, especially in uncompensated hearts, the conditions are reversed and C. W. > C. S. This is often the case. As a heart improves C. S. again tends to become greater than C. W. They think that the phases should be studied in respect to the sounds and also to the encroachment of one sound upon another. These observations are interesting but we have not found the division into phases as helpful as it was thought to be. We spent a great deal of time on this question. All that can be said, in my opinion, is that a loud, long third phase is usually evidence of cardiac strength. A further interesting feature which can be heard in all irregular hearts is a great difference in intensity of the individual sounds. Goodman and Howell call this phenomenon tonal arrhythmia. Irregularities can be made out by the auscultatory method which can not be heard at the heart. In anemia the sounds are very loud and clear and do not seem to represent the actual strength of the heart. The general lack of vasomotor tone in the blood vessels together with some atrophy and flabbiness of the coats probably explains the loud sounds. In polycythemia the sounds have a curious, dull, sticky character and can not be differentiated accurately into phases, a condition which was predicted from the knowledge of the sharp sounds in anemia. In not all cases can all phases be made out. It is usually the fourth phase which fails to be heard. In such cases the loud third tone almost immediately passes to the fifth phase or no sound phase. The importance of this will later be taken up.