ESSENTIALS OF PHYSIOLOGY. Sixth Edition, Edited and Revised by H. Hartridge. Longmans, Green and Company, I929. pp. 479. This book is very useful for students who wish to review the subject of human physiology, and for practitioners who are desirous of keeping abreast of the times. It quite lives up to its name, since the essentials of physiology are clearly presented, and not in such detail as...