Professor Herrick's book is a popular and picturesque presentation of the order of nature from the point of view of the experimental biologist. As far as its philosophy is concerned it might have come from the pen of Jacques Loeb. It is divided into four parts of which the first two deal with general concepts of mechanistic science and biology; the last two more specifically with psychological and human problems.

The concept "machine" is expanded by the author to include whatever performs work by natural agencies in accordance with natural laws, of which the law of causality is the most important. Since all nature works according to them and since throughout the