169 



between them. Like Professor Koch's book, it is intended mainly 

 for those who have to deal with pharmaceutical substances, but 

 it covers much more ground in that it treats of the micro- 

 structure of nearly all the drugs in general use, and also of many 

 substances used for food or in various manufactures. On the 

 other hand, it is not intended to be such a general work as 

 Hanausek's '' Lehrbuch der technischen Mikroskopie." 



The endeavour of the author has been to arrange the matter in 

 such a way that the student is led step by step from the com- 

 paratively simple and more easily investigated structures, to those 

 of greater and greater complexity. It is, therefore, only natural 

 that, after the inevitable " Allgemeiner Theil"on the microscope 

 .and its use, we should be introduced to those vegetable substances 

 usually met with in the form of powder, such as Lycopodium, Lupu- 

 lin, Kamala, and the starches. Then follow the fibres and fibre- like 

 structures, both animal and vegetable, leaves and flowers, seeds 

 and fruits, woods and barks, and finally the underground vegetable 

 productions and a few miscellaneous things such as galls, etc. 

 Particular attention is directed to the commoner forms of adultera- 

 ttion in cases where this is prevalent. There can be no doubt but 

 what this book will be of the greatest assistance to those interested 

 in any way in the subjects with which it deals, and its illustrations 

 make it quite a useful book of reference for the student of 

 structural botany. It is, in fact, the most copiously illustrated 

 publication of its kind that we have seen for a long time : four 

 hundred and nine figures, and nearly all of considerable size and 

 excellent quality, to three hundred and thirty-six pages. — D. J. S. 



Anleitung zum Gebrauch des Polarisationsmikroskops. By 



Dr. E. Weinschenk. 9 x 5| in., vi -}- 123 pages, 100 



figures in the text. Freiburg-r.-B,, 1901 : B. Herder. 

 Price 3 marks. 



The methods employed in the use of the polarising microscope, 

 or as it is more usually called in this country the mineralogical 

 or petrological microscope, are very rarely given in any detail in 

 books dealing with microscopical manipulation. This is the more 

 remarkable because this form of instrument is not limited in its 

 usefulness merely to the examination of thin sections of rocks 



