554 



THE POPULAR SCIENCE MONTHLY. 



suits set forth in this volume must of necessity 

 be full of imperfections. If it be asked why, 

 being thus conscious that far more time and 

 wider investigation are requisite for the proper 

 treatment of a subject so immense and involved, 

 I have undertaken it, my reply is that I have 

 been obliged to deal with political evolution as 

 a part of the general Theory of Evolution ; and, 

 with due regard to the claims of other parts, 

 could not make a more prolonged preparation. 

 Any one who undertakes to trace the general 

 laws of transformation which hold throughout 

 all orders of phenomena must have but an in- 

 complete knowledge of each order; since, to ac- 

 quaint himself exhaustively with any one order, 

 demanding, as it would, exclusive devotion of 

 his days to it, would negative like devotion to 

 any of the others, and much more would negative 

 generalization of the whole. Either generaliza- 

 tion of the whole ought never to be attempted, 

 or, if it is attempted, it must be by one who 

 gives to each part such time only as is requisite 

 to master the cardinal truths it presents. Be- 

 lieving that generalization of the whole is su- 

 premely important, and that no one part can be 

 fully understood without it, I have ventured to 

 treat of Political Institutions after the manner 

 implied : utilizing, for the purpose, the materi- 

 als which, in the space of fourteen years, have 

 been gathered together in the " Descriptive So- 

 ciology," and joining with them such further 

 materials as, during the last two years, have 

 been accumulated by inquiries in other direc- 

 tions, made personally and by proxy. 



Statistics of the Production of the 

 Precious Metals in the United 

 States. By Clarence King, Special 

 Agent of tbe Census. Washington : 

 Government Printing-Office. Pp. 94, 

 with Six Plates. 



The information on which this report is 

 based has been procured, so far as is possi- 

 ble, directly from the producers of bullion. 

 It was not expected that completeness could 

 be reached in this way, for many small pro- 

 ducers would be overlooked or would fail to 

 report, but the plan gives a nearer approach 

 to accuracy than can be gained from the 

 comparison of the receipts of domestic bull- 

 ion at the mints and assay-offices, or from 

 an examination of the bullion accounts of 

 the express companies the only other 

 sources of information that were open. A 

 comparison of the annual output of different 

 States shows that the United States produces 

 33-13 per cent of the gold yield of the 

 whole world, 50'59 per cent of the silver, 

 and 40 - 91 per cent of the total. Of the ag- 

 gregate supply of the precious metals, 

 North America furnishes ho'^lS per cent. 



IIand-Book of Invertebrate Zoology for 

 Laboratories and Seaside Work. By 

 W. H. Brooks, Ph. D. Boston : S. E. 

 Cassino. Pp. 392, 200 Cuts. Price, $3. 



This volume has very strong claims upon 

 the biological student ; but for the begin- 

 ner, especially if he lives near the sea, it is 

 incomparable. The art of starting a be- 

 ginner aright in any branch has not yet 

 been perfected, but Dr. Brooks has made a 

 successful stroke in this direction for zoo- 

 logical science. The work has been planned 

 with reference to the exigencies of system- 

 atic study, and to put the student upon 

 the right track to attain the mastery of the 

 subject with the least waste of exertion. 

 Nothing is introduced that is not want- 

 ed. Generalizations and comparisons are 

 omitted, on the principle that the beginner 

 shall first get at the facts, in order that he 

 may subsequently grasp and make the gen- 

 eralizations his own. The work is there- 

 fore not a text-book, but a hand-book of 

 practical study, and is admirably adapted 

 for self-instruction. In his prefatory re- 

 marks describing the work, the author says : 

 " Most lecturers upon natural science find, 

 no doubt, that preliminary work, the presen- 

 tation of facts upon which science is based, 

 absorbs so much time that there is no room 

 for a philosophical discussion of the scien- 

 tific aspects of the subject. I have there- 

 fore attempted to show the student how 

 to acquire a knowledge of the facts for him- 

 self, in order to remove this burden from 

 lecturers and text-books." 



The types selected for description are, of 

 course, but few compared with those con- 

 sidered in systematic works ; but still they 

 cover wide zoological ground, and are suffi- 

 cient to prepare for more comprehensive 

 research. In the treatment of each type 

 the author has not attempted to present all 

 that is known about it, but simply to guide 

 the beginner to those features which he can 

 find and observe for himself. And so also 

 with the illustrations. The minute details 

 of complicated structural figures are omit- 

 ted, and only those given that it is neces- 

 sary for the beginner himself to discover 

 in his examination of the specimens. For 

 this purpose, the illustrations are greatly 

 superior to any we have elsewhere seen. 



The book begins with the examination 



