viii EDITOR'S PREFACE. 



familiarity with the character of malt, hops, and 

 tobacco, which is evidenced in the following paper. 



He took to the microscope, partly for the love of 

 it, partly for its usefulness in his profession, and 

 partly, I think, because it gave him an excuse for 

 the practice of etching, an art of which he was 

 passionately fond, and in which the plates which 

 accompany this work show that he had attained no 

 mean proficiency. 



For years past the preparation of these plates, 

 and of the text which accompanies them, had been 

 the solace and occupation of his leisure ; and it was 

 his great ambition to publish them. But a few 

 months ago he fell into a rapid consumption, that 

 which carried off his elder brother twenty years ago, 

 and died without having seen more than the first 

 sheet in type. 



Critical readers will note much room for imj)rove- 



ment in the text of the little book; but on the 



whole, it seemed to me better not to attempt to do 



more than remove obvious errors, or supply the 



place of obvious deficiencies in a work which 



pretends to be but an imperfect memorial of an 



incomplete life. 



T. H. HUXLEY. 



