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XXV] of the voluntary muscles, the œdema of the connective tissue, and the serous effusions are, as a rule, not very serious matters at all events as affecting life. But it is very different when paresis and degeneration seriously implicate the heart and the muscles of respiration. In nearly all beriberics there is heart trouble, arising, doubtless, from implication of the pneumogastric nerve and the cardiac plexus. In some patients the degree of implication is slight; but in others it is sufficient so to weaken the heart that death is inevitable. We cannot be quite sure in which cases the implication of the pneumogastric nerve or cardiac plexus is likely to be serious, or in which cases it is likely to be slight. Often the mildest cases of beriberi, as judged by the degree of voluntary muscle paresis or by the amount of œdema, are in reality the most dangerous. There appears to be an element of chance determining the nerves which the poison picks out. Sometimes one may see a patient who is completely paralysed so far as legs and arms are concerned, and perhaps wasted to a skeleton; and yet this same patient may never have a serious symptom referable to his heart, or in any way threatening life. On the other hand, one may see a patient with very little paresis, very little œdema, and yet in a short time the heart may become involved, and he will die in a few minutes or hours.

I presume the dilatation of the heart, the usual cause of death, is favoured or brought about by a concatenation of several conditions: by degeneration of muscle fibre following nerve destruction, by imperfect systole in consequence of an interrupted nerve supply, by obstruction to capillary circulation in consequence of vaso-motor paresis in the pulmonary and general circulation. Once commenced, the cardiac dilatation tends to increase automatically; for the more the organ dilates the more difficult does it become for it to contract, the greater is the incompetency of the valves, and the more the blood stagnates in and over-distends it. The organ enters on a vicious pathological circle. Finally it becomes so distended that, like an overstretched bladder, it