434 



SCIENCE. 



[N. S. Vol. XVIII. No. 457. 



sented must convince the reader that the 

 topics discussed in the book are not only most 

 interesting, but are also those with which sci- 

 ence is to-day grappling. The method of pre- 

 sentation is also forceful, since it gains power 

 and simplicity because of the unifying in- 

 fluence of the great theory that pervades it 

 throughout. By thus giving a coherent treat- 

 ment of the problems that are in process of 

 solution at the present moment, Professor 

 Drude has produced a book that is bound to 

 have great influence for good upon the science 

 of optics, since it must impress the student 

 that, to use the author's own words, ' optics is 

 not an old worn-out branch of physics, but in 

 it there pulses a new life.' 



In doing this the author has in addition 

 given a valuable hint to writers of texts — for 

 how much greater would be the interest in 

 physical science among the people generally 

 if many of the time-worn, cut-and-dried (par- 

 ticularly dried) discussions that have clung 

 tenaciously to the texts could be rewritten so 

 as to present the subject entirely from the 

 present and future point of view instead of 

 from that of the past ? In such a presentation 

 stress would be laid, as Professor Drude has 

 done, not only upon that which had been set- 

 tled, but also upon that which still remains to 

 be settled; so that the reader would not be 

 tempted, after reading the book, to think that 

 he knows it all, since everything is finally set- 

 tled and he can and has committed it to 

 memory. 



Thus all students of physics owe a debt of 

 gratitude to the author of this ' Theory of 

 Optics,' not only because he has woven to- 

 gether for them the scattered threads of the 

 electromagnetic theory into a web of pleasing 

 and symmetrical pattern, but also because he 

 has, in so doing, shown how to present a scien- 

 tific subject in such a way that the student is 

 left with a realization of the fact that the sci- 

 ence is alive and teeming with future pos- 

 sibilities, instead of with a feeling of disgust 

 at having had thrust upon him the usual glori- 

 fied and embalmed image of past grandeur — 

 a corpse fixed in death. 



Thus this work impresses us as a very able 

 and original presentation of a difiicult sub- 



ject. We, therefore, welcome it as a distinct 

 addition to the literature of optics. We 

 congratulate the publisher on having made this 

 book accessible to those to whom German is 

 a barrier. They could perform another ser- 

 vice to science if they could persuade Pro- 

 fessor Drude to revise his earlier work on the 

 ' Physics of the Ether,' for this work helps 

 much in the understanding of his ' Theory of 

 Optics.' C. E. MjtNN. 



Uni\'eksity of Chicago, 

 September, 1902. 



Medical Microscopy. By T. E. Oertel, M.D. 



Philadelphia, P. Blakiston's Son & Co. 1902. 



Small 8vo. Pp. 362. 



The facts which a working knowledge of 

 microscopy may reveal to aid in diagnosis are 

 so important that the profession demands an 

 acquaintance with this subject which is 

 coming to be recognized more and more as 

 fundamental in medicine. 



This small volume is offered in response 

 to a legitimate voice, as the author believes, 

 coming especially from that part of the med- 

 ical profession which graduated before much 

 instruction was given in the subjects in which 

 the microscope seiwes so great a purpose. 



Naturally the microscope is the first to re- 

 ceive attention. The various parts are named 

 and their functions explained. The terms 

 used in manipulation are defined and some 

 of the phenomena are considered. 



The summary of the facts regarding the 

 habitat, pathogenesis, morphology and cultural 

 characteristics of many of the more important 

 pathogenic bacteria will be of much assistance 

 to those unfamiliar with the subject. The 

 following topics are also briefly treated: prep- 

 aration of tissue, tiunors, blood and the vari- 

 ous secretions and excretions of the body. 



An author is certainly justified in compiling 

 a work upon medical microscopy in order that 

 the rudiments of the somewhat scattered 

 knowledge may be accessible to all, yet, on the 

 other hand, when such a book compiled from 

 works upon subjects which are experiencing 

 such rapid changes and additions reaches the 

 reader, there will be an opportunity to take 

 exceptions to certain portions of it. This 



