April 22, 1910] 



SCIENCE 



625 



Specific chemical substitutions are accompanied 

 by definitely orientated changes of the crystal 

 structure, indicating that particular chemical 

 atoms occupy definitely localized positions in the 

 chemical molecule, and therefore, as the molecule 

 is the structural unit of the space-lattice, in the 

 crystallographic structural unit. 



This last principle, first definitely estab- 

 lished by these researches, is regarded by the 

 author as the most marked step in advance 

 he has made. 



Despite its highly specialized character the 

 book is written in a style that is delightful 

 and should surely be in the possession of every 

 student of physical crystallography. 



Charles Palache 



Elements of Mineralogy, Crystallography and 

 Blowpipe Analysis from a Practical Stand- 

 point. By Alfred J. Moses, E.M., Ph.D., 

 Professor of Mineralogy, Columbia Univer- 

 sity, and Charles L. Parsons, B.S., Pro- 

 fessor of Chemistry, New Hampshire Col- 

 lege. Fourth edition, with 448 pages of 

 test and 583 figures. Cloth, 6 X 9*- New 

 York, D. Van Nostrand Company. 1909. 

 $2.50 net. 



The fourth edition of this well-known text- 

 book differs in no essential matters from the 

 previous edition. The statistics of production 

 of minerals of economic value have been re- 

 vised, the figures given being those for 1907 

 and in part 1908. The book gives an excellent 

 presentation of the main facts of mineralogy 

 and deserves to be, as it doubtless is, largely 

 used by teachers of the subject. 



It is unfortunate that advantage has not 

 been taken of the opportunity offered by this 

 new edition to improve some of the very poor 

 illustrations that mar certain pages, as well 

 as to eliminate several confusing errors in the 

 crystallographic figures and lettering. 



Charles Palache 



Indian Insect Life. A manual of the insects 

 of the plains (Tropical India). By H. 

 Maxwell-Lefroy, Entomologist, Imperial 

 Department of Agriculture for India, and 

 P. M. HowLETT, 2d Entomologist, published 

 under the authority of the Goveriiment of 

 India, Agricultural Research Institute, 



Pusa. 4to, pp. 786, plates 84 (many col- 

 ored), text figures 536. Calcutta and 

 Simla, Thacker, Spink & Co.; W. Thacker 

 & Co., 2 Creed Lane, London. 1909. 

 This attractive and well-illustrated volume 

 gives, in convenient form, a summary account 

 of the varied insect life of tropical India, in 

 particular. This limitation necessarily pre- 

 cludes the discussion, except in an incidental 

 manner, of the splendid fauna of the Hima- 

 layan region. There is much of interest in 

 the work for the professional entomologist, 

 while the amateur will find a large number of 

 the more conspicuous or common insects 

 noticed, accompanied in many instances by 

 facts of great practical value. 



The author finds it convenient to treat the 

 varied forms under nine orders, namely, 

 Aptera, Orthoptera, Neuroptera, Hymenop- 

 tera, Coleoptera, Lepidoptera, Thysanoptera, 

 Diptera and Ehynehota (Hemiptera) follow- 

 ing, in a large degree, the classification 

 adopted by Sharp. The author's aim has 

 been to produce a readable, convenient vol- 

 ume rather than to rigidly follow a classifica- 

 tion with possible inconvenience to his read- 

 ers. The introduction gives some observations 

 upon the principles of classification, the re- 

 lation of instinct and habit, the sources of 

 information, and a discussion of the zoogeo- 

 graphical divisions of India, the faunal limits 

 of the work thus being plainly defined. At 

 the outset, insects are roughly classified ac- 

 cording to food habits, they being divided, for 

 example,- into fruit insects, seed-eating in- 

 sects, flower insects, etc. There is an illumi- 

 nating chapter on insects and their relations 

 to man, a much more vital topic in the tropics 

 than in the temperate zone. 



The space given to the discussion of the 

 orders is necessarily unequal, owing to the 

 fact that representatives of many Indian 

 groups are comparatively unknown. A most 

 attractive feature for the general student is 

 found in the independent chapters or inter- 

 ludes dealing with such topics as: Where In- 

 sects Live, Cosmopolitan Insects, Deceptive 

 Coloring, Relative Duration of Life, Insects 

 and Flowers, How Insects Protect Themselves, 

 etc., each of these summarizing from the en- 



