VI PREFACE. 



years later a different arrangement was made ; the students 

 were required to perform the experiments for themselves, 

 and at the same time laboratory work in the chemistry of 

 metabolism was organised by Mr Acton. To enable the 

 students to carry out their work, written instructions 

 were needed, and the present book is the result of an 

 extension and elaboration of what we prepared for our 

 classes. 



The book makes no pretence to completeness, it 

 contains merely such a selection of experimental and 

 analytical work as seems suitable for botanical students. 



Part I, which deals with general physiology, is 

 necessarily of a somewhat more elementary character 

 than Part II, which treats a particular department of 

 physiology in a more special manner, and presupposes a 

 greater amount of knowledge on the part of the student. 



Owing to the Second Edition having being stereotyped 

 the changes in the present edition have been necessarily 

 limited in number. The chief additions are : Exp. 5 

 (the Bonnier-Mangin apparatus), Exp. 48 A (Farmer's 

 method of demonstrating assimilation), Exp. 61 A (an 

 optical effect with chlorophyll solution), Exp. 118 (the 

 Horn-hygroscope), Exp. 118 bis (the temperature of 

 leaves), Exp. 206 (the localisation of the sensitive region 

 in Setaria, &c.). 



