554 NATURAL SCIENCE. X." 



sections, a chemical analysis of the efficacious portion, its physio- 

 logical action, the way to use it, and the dose. In several cases 

 glucosides and alkaloids have been for the first time isolated, or 

 thoroughly studied, e.g., mikanine from Mikania guaco, condurangine 

 from Gonolohiis condurango, dorstenine, and others. 



The physiological action of plants, or the chemical compounds 

 produced in the course of their metabolism is a subject always 

 deserving of study, both from a medical and scientific point of view, 

 and it may be of use to have collected in one volume such a class as 

 those treated of in " Les Plantes Alexiteres de I'Amerique." 



Mineralogy. By F. H. Hatch, Ph.D., F.G.S. Pp. 124, figs. 115. London: 

 Whittaker & Co., 1892. Price 3s. 6d. 



This little volume, which belongs to Whittaker's Library of Popular 

 Science, should prove useful as an elementary introduction to the 

 scientific study of minerals, and in our opinion it differs from other 

 English or American text-books of Mineralogy in precisely those 

 features which make a book suitable for beginners. 



The author refrains from describing many species or from entering 

 into much detail, and the minerals selected for description are grouped 

 according to those properties from which they derive their interest or 

 importance. A brief introduction concerning the Characters of 

 Minerals is succeeded by four short chapters on (i) Rock-forming 

 Minerals, (2) Ores and Veinstones, (3) Salts and Useful Minerals, (4) 

 Gems. This arrangement is evidently more attractive, and, we 

 venture to think, more useful to a beginner than the customary method 

 of describing one species after another in systematic order. 



The book is of a quite elementary and popular character, and is 

 written in the simple and lucid style which distinguished Dr. Hatch's 

 " Introduction to Petrology." We can find nothing in this volume 

 which should not be easily intelligible, except the explanation of 

 cleavage on p. 36, of which the meaning is by no means apparent. 

 Some of the figures are reproductions from photographs of specimens. 



