al, with a view to diminishing
the injury caused to society by his anti-social acts; also to
superintendents, teachers, and those engaged in rescuing orphans and
children of vicious habits, as a guide in checking the development of
evil germs and eliminating incorrigible subjects whose example is a
source of corruption to others.

* * * * *

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, $1.65

It is not often that a scientific book may be read with ease, profit,
and pleasure by the general reader, so that M. Metchnikoff's book
comes in the nature of an agreeable surprise. It is marked by a
refreshing _naivete_ and a large simplicity which are
characteristically Russian. The scientific 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 distinguished
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--G. P. Putnam's Sons--London

* * * * *

"_Remarkable for its simple language and clear
style.... Bears the stamp of a production of
an erudite scientist and a deep thinker._"--Science.

The Prolongation of Life

Optimistic Essays

_By_ Elie Metchnikoff

_Author of "The Nature of Man," etc._

_8vo. Illustrated Popular Edition. $1.75 net By mail, $1.90_