PEEFACE. 



EDWARD HAMILTON ACTON died in the early part 

 of 1895. This is not the place to speak of what we, 

 his friends, have lost by his death, nor of his promising 

 career as a man of science. All that I can do here is to 

 explain in what way I have dealt with that part of the 

 book for which he was especially responsible. 



Part II, on the chemistry of metabolism, was entirely 

 written by Mr Acton, and is here reprinted practically as 

 he left it. The only changes are two or three corrections 

 found in his interleaved copy of the book, and a few verbal 

 and typographical alterations introduced for the sake of 

 uniformity. 



The book (as explained in the preface to the 1st Edition) 

 originated in the following way. 



In 1883 I began a course of instruction in the 

 physiology of plants, of which the chief feature was the 

 demonstration of experiments in the lecture-room. Some 



