The most valuable production since Darwin's " Origin 

 of Species." 



The Nature of Man 



Studies in Optimistic Philosophy 

 By Elie Metchnikoff 



Sub-Director of the Pasteur Institute, Paris 



Translated with an Introduction by 



P. Chambers Mitchell 



Secretary of the Zoological Society 

 Octavo. Illustrated. Popular Edition. $1.50 net. By mail, $x.Cg 



It Is not often that a scientific book may be read with 

 ease, profit, and pleasure by the general reader, so that 

 M. Metchnikoft's book comes in the nature of an agreeable 

 surprise. It is marked by a refreshing nawet& and a large 

 simplicity which are characteristically Russian. The scien- 

 tific importance of this work is so great that it is spoken of 

 in England as the most valuable production since Darwin's 

 Origin of Species. 



Opinions of the Press 



*'An extremely interesting and typical book. ... With a distin- 

 guished frankness, M. Metchnikoff defines his attitude to our universal 

 prepossessions. It is his theory that the infirmities of age are to be 

 overcome. If there be ground for this conception, humanity is to be 

 profoundly changed and what we call life now, will be the childhood 

 and youth of that longer and larger life." H. G. WELLS, in London 

 Speaker. 



" Undoubtedly a great book (in some quarters it has been hailed as 

 the greatest since Darwin's famous message to the world) and should 

 be read by all intelligent men and women." The Nation. 



" A book to be set side by side with Huxley's Essays, whose spirit It 

 carries a step further on the long road towards its goal." Mail and 

 Express. 



New York Q. P, Putnam's Sons London 



