Page:Popular Science Monthly Volume 49.djvu/146

134 conceive as nebula, consisting of particles smaller than the chemical atoms, and to this he gives the name "pneuma." He supposes the pneuma to consist not of a single nor a few elements, but of a much larger number than we now know—possibly exceeding ten thousand. He then goes on to describe how these particles might combine to form atoms and how an immense pneuma might condense to form a core around which revolved masses formed from rings that had been detached as the process advanced. In this, and in accounting for the rotation of the several members of such a system, he is not greatly at variance with current theories. His view of comets makes them quite regular members of a planetary system. In the more particular examination of the history and present condition of the earth, which follows, he suggests the possibility of some continental elevations being formed by the projection of cold planetoids upon the molten globe. The probable effect upon the condensing earth of the formation of the inferior planets is then discussed, and, in conclusion, an effort is made to correlate the geological periods, including the Glacial epoch, with astronomical phenomena. The author has read papers upon some of the topics discussed in this book before various learned societies in England. The volume is illustrated with several plates and small cuts.

Food Products of the World is the title of an interesting volume by M. E. Green, M. D. (Chicago, The Hotel World). The original intention of the author, who was one of the judges of food products at the Columbian Exposition in 1893, was simply to give an account of the foods there exhibited; but as the work progressed it was deemed desirable to expand the treatment somewhat and make a popular treatise, which should in a fairly thorough manner cover the whole subject. Each food stuff is first treated in a general way. Its history, preparation, cooking, and keeping qualities; its habitat, if animal or vegetable; and, finally, the chemical composition and dietetic value, are given.

Since the appearance of the first edition of this work, Sedgwick and Wilson's Introduction to General Biology (Holt, Sl.'ZS), in 1886, the original intention of the authors, to publish a second volume which was to form the main body of the work, and to include the study of a series of type forms, has been abandoned. The present volume, in consequence of this, differs in several particulars from the first edition. The introduction has been extended so as to include representatives of the unicellular organisms, amœba, infusoria, protococcus, yeasts, bacteria. The study of the animal is placed before that of the plant, and the laboratory directions, which occur in the first edition, having been found unsuitable, are omitted. The general subject matter has been revised and many additions made, especially on the physiological side.

We are convinced from an examination of the text-book on Organic Chemistry: the Fatty Compounds, by H. Lloyd Whiteley (Longmans, 3s. 6d.—$1), that its author possesses a high degree of the teaching faculty. He seems to build up a knowledge of the carbon compounds in the student's mind by starting with a few general ideas and adding others in the order and manner in which they can be best assimilated. He is careful also to distinguish what is demonstrable experimentally from what is obtained by reasoning or is assumed as a means of expressing empirical results. He is concise, too, managing to describe in a small volume the fatty hydrocarbons, haloid paraffins, monohydric alcohols and their several classes of derivatives, the cyanogen and carbonic-acid derivatives, the derivatives of unsaturated hydrocarbons, and the dihydric and polyhydric alcohols and their derivatives. Processes for the preparation of a large number of compounds are given, a distinguishing mark being placed against those most suitable for students' work. Commercial processes for producing the most important substances are outlined. There are forty-five cuts, nearly all of laboratory apparatus.

In Essentials of Vegetable Pharmacognosy the gross structure of plants is set forth by Henry H. Rusby, M. D., and their minute structure by Smith E. Jelliffe, M. D. (Haynes, New York). The former monograph begins with the structure of the flower, and passes on to its functions and the production of fruit. The root, stem, and leaf are then considered in succession, after which phyllotaxy and anthotaxy are discussed. The