THE MICROSCOPE. 27 
larly free from pathogenic microdrganisms. In fact, the only patho- 
genic organisms as yet definitely discovered and established by inocu- 
lation examinations are the ubiquitous St phylococcus pyogens 
aurens and streptococcus of erysipelas. 
BOOK “REVVEW 3; 
MIcRoGRAPHICAL PHYSIOGRAPHY OF THE RocK-MAKING MINERALS; An 
aid to the microscopical study of rocks. By H. Rosenbusch. Translated 
and abridged for use in schools and colleges by Joseph P. Iddings. 121 
wood cuts and 26 protomicrographic plates. New York: John Wiley & 
Sons. 1888: pp. 333. 
The old and hackneyed phrase, “ fills a long-felt want,” is very 
pertinent in describing this work. Although open to the German- 
reading scientist for the past fifteen years, Prof. Rosenbusch’s man- 
ual has, up to the present time, had no English translator, thus 
bringing it within the reach of the public. That a beginning only 
has been made in the microscopical investigation of rock is well 
known ; that their preparation and study is as fascinating and 
absorbing as work in other departments is not yet appreciated. Dr. 
Idding’s book will accomplish much in making the way plain to 
older microscopists, while beginners will be stirred to explore new 
fields, which offer so much in the way of discovery. We regret that 
our limited space will not allow us to give a detailed description of 
this excellent book, for we consider it one of the greatest importance 
to the geologist and microscopist. We may say, however, that it is 
just the guide which we have been looking for, and we strongly recom- 
mend it to all those whose inquiries for a reliable work on microscopical 
petrology have heretofore been answered negatively. The translat- 
ing has been well done, and the illustrations, especially the photo- 
micrographic plates, will be found of much assistance to the student. 
Ler’s OrriciAL Map oF THE Crry oF PrirTsBURGH, 1888. 
This is an excellent colored lithographic bird’s-eye view of Pitts- 
burgh, Alleghany, and surrounding towns, showing the location of the 
various manufacturing interests, and answering the question, ‘‘ why 
all roads will lead to Pittsburgh in September ?” 
LORENZ, WEICHNACHTS UND LAGER BCHER-CATALOGUE. 
Our German agent, Mr. Alfred Lorets, has issued his attractive 
annual catalogue of miscellaneous books for the holidays. 
