to solve. They cannot but prove to be of enduring value, whether 

 for the information of the general reader or as guides to investi- 

 gators occupied with problems similar to those which engaged the 

 attention of Darwin. 



The essayists have been fortunate in having for reference the 

 five published volumes of Charles Darwin's Life and Correspondence. 

 For there is set forth in his own words the inception in his mind 

 of the problems, geological, zoological and botanical, hypothetical 

 and theoretical, which he set himself to solve, and the steps by 

 which he proceeded to investigate them with the view of corre- 

 lating the phenomena of life with the evolution of living things. 

 In his letters he expressed himself in language so lucid and so 

 little burthened with technical terms that they may be regarded 

 as models for those who were asked to address themselves primarily 

 to the educated reader rather than to the expert." 



As a text to this volume is given the memorable passage from 

 the Autobiography of Charles Darwin, in which the great naturalist 

 sums up the story of his life of research and of comparison: 



" My success as a man of science, whatever this may have 

 amounted to, has been determined, as far as I can judge, by com- 

 plex and diversified mental qualities and conditions. Of these, the 

 most important have been the love of science unbounded patience 

 in long reflecting over any subject industry in observing and col- 

 lecting facts and a fair share of invention as well as of common 

 sense. With such moderate abilities as I possess, it is truly sur- 

 prising that I should have influenced to a considerable extent the 

 belief of scientific men on some important points." 



Of special interest, from an agricultural point or view, are the 

 following Essays contained in this volume: 



AUGUST WEISMANN, " The Selection Theory." 



W. BATESON, " Hereditary and Variation in Modern Lights." 



HUGO DE VRIES, " Variation." 



E. STRASBURGER, "The Minute Structure of Cells in Relation 

 to Heredity." 



GEORG KLEBS, " The Influence of Environment on the forms 

 of Plants." 



J. LOEB, " Experimental Study of the Influence of Environment 

 on Animals." 



W. THISELTON-DYER, " Geographical Distribution of Plants." 



H. GADOW, " Geographical Distribution of Animals." 



K. GOEBEL, " The Biology of Flowers." 



