It is hoped that this new arrangement will prove satisfactory to students. It has the advantage that the book still covers the whole ground, while remaining of a manageable size, and that it is closely linked up with a series of similar books, each dealing with separate sections, in which more complete treatment and more fully informed criticism are given than I could myself undertake. On the other hand, the necessity for freedom of treatment, and the difficulty of placing such subjects as Soil Physics or Soil Protozoa under the heading of Biochemistry, compelled the withdrawal of the book from the important Biochemical Series, of which it has hitherto been a member. And, although Drs. Plimmer and Hopkins willingly consented, this course was not taken without serious consideration and regret: it in volves the separation of the book from a very useful series of volumes.