618 



SCIENCE. 



[N.S. Vol. XXV. No. 642 



to a discussion of the theory of light, its re- 

 flection, refraction and polarization, the man- 

 ner in which it is acted upon by isotropic, 

 uniaxial and biaxial crystals, and finally how 

 these properties may be made of determina- 

 tive value by means of a properly constructed 

 microscope, the various appliances and method 

 of application of which are fully explained. 

 Pages 201-526, inclusive, are devoted to de- 

 tailed discussions of the characteristics of the 

 individual species of the rock minerals. Here 

 the author is at his best, and has left little 

 to be desired in the way of clear and ex- 

 haustive treatment. Each mineral is con- 

 sidered with regard to its chemical composi- 

 tion, alteration, crystal form, optical proper- 

 ties, color, inclusions, mode of occurrence, 

 resemblances and laboratory reproduction, in 

 the order here given. The arrangement of 

 the minerals, on a chemical basis, strikes one, 

 however, as a trifle illogical, since the methods 

 of determination are almost wholly optical 

 and one who has worked with the book of 

 liosenbusch will at flrst find it awkward. 

 Pages 527-541 are devoted to tables giving 

 these optical characters. The book is illus- 

 trated by upwards of four hundred figures — 

 mostly crystal outlines — in the text. Many 

 will miss the plates of micrographs of thin 

 sections found in the work of Rosenbusch, 

 but it is possible that Professor Iddings, as a 

 teacher, wished to guard the student against 

 the danger of relying too much upon the ap- 

 pearance of a mineral rather than upon its 

 optical properties. The adoption of a new 

 system of numbering with each change of sub- 

 ject, though the same as that used by Dana 

 in his system of mineralogy, is a little con- 

 fusing to one turning the leaves at random, 

 but inasmuch as each figure occurs on the 

 page of text in which reference to it is made, 

 no serious confusion is likely to arise. 



The book is of good size and form for con- 

 venient use, well printed and bound, and that 

 it is essential to every student and teacher 

 must be self-evident. George P. Merrill 



The Human Mechanism, its Physiology and 

 Hygiene, and the Sanitation of its Sur- 

 roundings. By Hough and Sedgwick. 

 Boston, Ginn & Company. 



This book adds another to a series of very 

 useful text-books on the subject of physiology 

 designed for secondary schools. It is, how- 

 ever, rather unique among the series in several 

 respects, the more distinctive of which the 

 present review will endeavor to point out. 



First among them is the point of view from 

 which the authors approach the subject, name- 

 ly, as implied in the title. The human tody 

 as a mechanism. This conception the authors 

 regard as "not only the sure foundation of 

 physiology, hygiene and sanitation, but is also 

 surprisingly helpful in the solution of many 

 questions concerned with intellectual and 

 moral behavior." 



A second feature upon which emphasis is 

 placed is the conception of the mechanism as 

 a whole. "Avoiding that form of physiology 

 which looks chiefly at the organs and overlooks 

 the organism, we have constantly kept in view 

 the body as a whole, in order that physiology 

 may become the interpreter of the common 

 physical phenomena of the daily life and find 

 in hygiene and sanitation its natural applica- 

 tion in conduct." In this view there will 

 doubtless be general concurrence. 



Still a third feature, more or less distinctive, 

 is the large consideration given to problems 

 of sanitation, both domestic and public. So 

 far as the reviewer is aware, this is the only 

 text-book designed for schools in which this 

 aspect of physiology has received the degree 

 of attention it deserves. Just how far this 

 may properly come within the scope of the 

 average school course will doubtless be a mat- 

 ter of divided opinion ; as may likewise be the 

 further query as to how far details of sanitary 

 principles come within the intelligent appre- 

 hension of the average pupil of the grades 

 likely to be affected. But allowing for such 

 debatable differences, it would seem that pro- 

 vision should be made for some insight into 

 this increasingly important subject. To the 

 vast majority of pupils of the high school this 

 will be about the only opportunity for such 

 insight, and it is the reviewer's conviction 

 that the authors have done well to put it well 

 to the front in their book. 



There is another point, however, mainly a 

 pedagogical one, which seems open to some 



