Among the most evasive of solution among biologic problems are problems of how plants and animals attain and maintain their form and organization. In the small book which is being reviewed, S. J. Holmes, who was among the earlier biologists who labored with these problems, has developed historically many of the proposed hypotheses together with their defending or opposing arguments. He has also attempted to add to the story such recent biologic information as may contribute to the solution of the problem.
In the first chapter, entitled "The Problem of Organic Form," the author has presented in a general way the questions which are to be answered. Starting with the points of view of Pflüger and Roux, he continues with those of Child, Driesch, McDougall, Cannon and others. Fortunately he directs his discussion away from teleologies and entelechies.
In the following twelve chapters the author deals with specific fields of