This is in part a condensation of the second edition. In bringing it down to date, Orr has been careful not to sacrifice the clinical character of the earlier work. He has made it representative of the newer views of Mackenzie that were largely the result of the investigations carried on at the St. Andrew's Institute for Clinical Research. Thus there are the now familiar views concerning heart failure, cardiac irregularities and heart murmurs. Especial stress is laid on the principle of the reflex arc. The favorable comments made in The Journal in the review of the earlier editions still obtain. The work has been well done, and the author's views are in the main sound and clearly expressed. An intelligent layman can understand much. There is a great deal of value, especially in the way of stimulating hints to the undergraduate and the practitioner.