Irregularity of the pulse, a total derangement of its rhythm, while not often important in young children, is a serious symptom at other times of life. In one disease most common in childhood, acute hydrocephalus, the pulse in the first stage is apt to be hard and rapid, in the middle stage slow and tolerably full, in the third rapid, feeble, and often irregular. Mitral disease frequently presents considerable irregularity of the pulse; and so does dilatation, even without mitral lesion. Brain trouble, especially late in life, whether structural or functional, may produce the {156} same symptom. B. W. Richardson has pointed this out as one of the effects of the excessive use of tobacco, even in young persons. The pulse of continued, relapsing, and remittent fevers is, during the febrile exacerbation, rapid (100 to 120); in the earlier part of the attack full, but only moderately hard, or even soft and yielding. As the attack passes its height and critical defervescence occurs, the pulse grows slower, unless great prostration has supervened; in which case it increases in rapidity, while it fails more and more in fulness and resistance. The pulse of the moribund state is nearly always small, very rapid (130-150), and thready, without force or fulness. It may become imperceptible before death. A pulse of 140 beats in the minute is always alarming; if much beyond that rate the case is desperate. A pulse of more than 150 beats in the minute is very difficult to count accurately. Exophthalmic goitre is attended characteristically by a full, somewhat rapid, and bounding pulse, the cardiac impulse being also proportionately violent and extended. Exercise much increases this hyper-pulsation. Pulsation of the jugular veins is ordinarily explained by tricuspid regurgitation, a portion of the blood being sent back to the vena cava with an impulse reaching to the jugulars. In some instances, however, as the writer has repeatedly observed, jugular pulsation takes place without any abnormality in the action or condition of the heart, from a local inflammation (as tonsillitis) causing a marked exaggeration of the muscular contractility resident in the larger veins. Retardation of the flow of blood through the veins is manifest during the collapse of epidemic cholera. On pressing the blood back in a vein upon the hand, for example, and then lifting the finger, instead of the movement being, as in health, too swift to be seen, it is so slow as to be easily followed.