ZOOLOaY AND BOTANY, MICROSCOPY, ETC. 91 



acids promoting this conversion by means of starcli in a remarkable 

 manner. Absence of these acids not only decreases the transforma- 

 tion of starch but also the turgidity of the cells ; but this conversion 

 can only be effected by the combined action of the acid and of the 

 ferment. 



Formation of Ferments in the Cells of Higher Plants.*— A 

 series of experiments by W. Detmer leads him to the conclusion that 

 in the cells of higher plants no transforming ferment can be pro- 

 duced in the absence of oxygen. Access of free oxygen is an essential 

 condition for the formation of diastase, and the ferment is unques- 

 tionably formed by means of oxygen out of the albuminoids or proteids 

 of the protoplasm. 



Ponlsen's Botanical Micro-Chemistry. f — This book, after having 

 been translated from the original Danish into German, French, and 

 Italian, at last appears in English, having been translated, with tha 

 assistance of the author, and considerably enlarged by Professor W. 

 Trelease, of Wisconsin, U.S.A. 



We referred to the original work (i. 1881, p. 772) but we may 

 quote the following paragraphs from the introduction as showing its 

 scope: — 



" Physics has thus striven to bring the Microscope to as great a 

 degree of perfection as possible ; it remains for chemistry to find 

 means of recognizing and rightly understanding the composition of 

 the objects we investigate. In other words, if we employ a thorough 

 system of chemical analysis with the optical apparatus, we shall be 

 able to answer all questions lying within the range of possibility. It 

 is this analysis applied to objects under the Microscope that we 

 designate by the word micro-chemistry. 



I have endeavoured to successively make the reader acquainted 

 with the most valuable reagents used in micro-chemistry, i.e., 

 with those substances whose action on the bodies to be studied 

 allows their chemical composition and nature and sometimes 

 their physical structure to be recognized. In the first section I 

 have considered the chemicals iised in the laboratory ; in the second, 

 the vegetable substances to be tested for, and the reactions by which 

 they are known ... At the close of the first section I have intro- 

 duced a short chapter on media for the preservation of permanent 

 preparations, to which are added a few words on the cements used in 

 mounting." 



The book ought to be in every microscopist's library. 



* Bot. Ztg., xli. (1883) pp. 601-6. 

 t See infra, Bibliography a. 



