PREFACE. V 



Of letters addressed to my father I have not made much 

 use. It was his custom to file all letters received, and when 

 his slender stock of files ("spits" as he called them) was 

 exhausted, he would burn the letters of several years, in order 

 that he might make use of the liberated " spits." This process, 

 carried on for years, destroyed nearly all letters received 

 before 1862. After that date he was persuaded to keep the 

 more interesting letters, and these are preserved in an 

 accessible form. 



I have attempted to give, in Chapter III., some account ot 

 his manner of working. During the last eight years of his 

 life I acted as his assistant, and thus had an opportunity of 

 knowing something of his habits and methods. 



I have received much help from my friends in the course of 

 my work. To some I am indebted for reminiscences of my 

 father, to others for information, criticisms, and advice. To all 

 these kind coadjutors I gladly acknowledge my indebtedness. 

 The names of some occur in connection with their contribu- 

 tions, but I do not name those to whom I am indebted for 

 criticisms or corrections, because I should wish to bear alone 

 the load of my short-comings, rather than to let any of it fall 

 on those who have done their best to lighten it. 



It will be seen how largely I am indebted to Sir Joseph 

 Hooker for the means of illustrating my father's life. The 

 readers of these pages will, I think, be grateful to Sir Joseph 

 for the care with which he has preserved his valuable collec- 

 tion of letters, and I should wish to add my acknowledgment 

 of the generosity with which he has placed it at my disposal, 

 and for the kindly encouragement given throughout my work. 



To Mr. Huxley I owe a debt of thanks, not only for much 

 kind help, but for his willing compliance with my request that 



