PREFACE 



to remain in letters mainly concerned with another 

 subject. For these irregularities we must ask the 

 reader's patience, and beg him to believe that some 

 pains have been devoted to arrangement. 



l\Ir. Darwin, who was careful in other things, 

 generally omitted the date in familiar correspondence, 

 and it is often only by treating a letter as a detective 

 studies a crime that we can make sure of its date. 

 Fortunately, however, Sir Joseph Hooker and others 

 of Darwin's correspondents were accustomed to 

 add the date on which the letters were received. 

 This sometimes leads to an inaccuracy which needs 

 a word of explanation. Thus a letter which Mr. 

 Darwin dated "Wednesday" might beheaded by us 

 "Wednesday [Jan. 3rd, 1867]," the latter half being 

 the date on which the letter was received ; if it 

 had been dated by the writer it would have been 

 "Wednesday, Jan. 2nd, 1867." 



In thanking those friends — especially Sir Joseph 

 Hooker and Mr. Wallace — who have looked through 

 some of our proof-sheets, we wish to make-it clear that 

 they are not in the smallest degree responsible for our 

 errors or omissions ; the weight of our shortcomings 

 rests on us alone. 



We desire to express our gratitude to those 

 who have so readily supplied us with information, 

 especially to Sir Joseph Hooker, Professor Judd, 

 Professor Newton, Dr. Sharp, Mr. Herbert Spencer, 

 and Mr. Wallace. And we have pleasure in men- 

 tioning Mr. H. W. Rutherford, of the University 

 Library, to whose conscientious work as a copyist 

 we are much indebted. 



Finally, it is a pleasure to express our obligation 



