PREFACE. XI 



which without his assistance I could scarcely have spoken. It is 

 impossible for me adequately to express my obligation to Dr Sharp 

 for his constant kindness, for the many suggestions he has given 

 me, and for the generosity with which he has put his time and 

 skill at my service. 



It is with especial pleasure that I take this opportunity of 

 offering my thanks to Professor Alfred Newton for the encourage- 

 ment and sympathy he has given me now for many years. 



As many of the subjects treated involve matters of interpret- 

 ation it should be explicitly declared that though help has been 

 given by so many, no responsibility for opinions attaches to anyone 

 but myself unless the contrary is stated. 



The blocks for Figs. 18, 19, 25, 133, 161 and 185 (from Proc. 

 Zool. Soc.) were very kindly given by the Zoological Society of 

 London; that for Fig. 28 (from Trans. Path. Soc.) by the Pathological 

 Society; and for Fig. 140 which is from the Descent of Man I am 

 obliged to the kindness of Mr F. Darwin. Figs. 5 B, 5 C, and 77 were 

 supplied by the proprietors of Newman's British Butterflies, and 

 Figs. 5 A, 82 and 84 by the proprietors of the Entomologist. The 

 sources of other figures are acknowledged under each. Those not 

 thus acknowledged have been made from specimens or from my 

 own drawings or models by Mr M. P. Parker, with the exception 

 of a few specially drawn for me by Mr Edwin Wilson. 



The work was, as I have said, begun in the earnest hope that 

 some may be led thereby to follow the serious study of Variation, 

 and so make sure a base for the attack on the problems of 

 Evolution. Those who reject the particular inferences, positive 

 and negative, here drawn from that study, must not in haste 

 reject the method, for that is right beyond all question. 



That the first result of the study is to bring confusion and 

 vagueness into places where we had believed order established 

 may to some be disappointing, but it is best we deceive ourselves 

 no longer. That the problems of Natural History are not easy but 

 very hard is a platitude in everybody's mouth. Yet in these days 

 there are many who do not fear to speak of these things with 

 certainty, with an ease and an assurance that in far simpler 

 problems of chemistry or of physics would not be endured. For 

 men of this stamp to solve difficulties may be easy, but to feel 



