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POPULAR SCIENCE MONTHLY. 



conceive as nebula, consisting of particles 

 smaller than the chemical atoms, and to 

 this he gives the name " pneuma." He sup- 

 poses the pneuma to consist not of a single 

 nor a few elements, but of a much larger 

 number than we now know possibly ex- 

 ceeding 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 regu- 

 lar 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 con- 

 densing 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 as- 

 tronomical phenomena. The author has 

 read papers upon some of the topics dis- 

 cussed in this book before various learned 

 societies in England. The volume is illus- 

 trated 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 com- 

 position and dietetic value, are given. 



Since the appearance of the first edition 

 of this work, Sedgwick and Wilson's Intro- 

 duction to General Biology (Holt, $1.*75), 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 in- 

 clude the study of a series of type forms, has 

 been abandoned. The present volume, in 

 consequence of this, differs in several par- 

 ticulars from the first edition. The intro- 

 duction has been extended so as to include 

 representatives of the unicellular organisms, 

 amoeba, 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 physiologi- 

 cal side. 



We are convinced from an examination 

 of the text-book on Organic Chemistry : the 

 Fatty Compounds, by R. Lloyd Whiteley 

 (Longmans, 3s. &d. $1), that its author pos- 

 sesses 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 ex- 

 perimentally from what is obtained by rea- 

 soning or is assumed as a means of express- 

 ing empirical results. He is concise, too, 

 managing to describe in a small volume the 

 fatty hydrocarbons, haloid paraffins, mono- 

 hydric alcohols and their several classes of 

 derivatives, the cyanogen and carbonic-acid 

 derivatives, the derivatives of unsaturated 

 hydrocarbons, and the dihydric and polyhy- 

 dric 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 Pharmacog- 

 nosy 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 con- 

 sidered in succession, after which phyllotaxy 

 and anthotaxy are discussed. The treat- 



