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LEADERS IN SCIENCE SERIES.

12MO, FULLY ILLUSTRATED. EACH, $1.50

I.-The Life and Work of Charles Darwin. By
CHARLES F. HOLDER.

"Mr. Holder is one of the American savants who have made Darwin and his system of philosophy a subject of profound study, and his book relating to him is one of the best that has been produced for popular use." -Philadelphia Bulletin.

"The sketch of this life is just, sympathetic, and brief-three good points in a biography."-Springfield Republican.

II. The Life and Works of Louis Agassiz.—By
CHARLES F. HOLDER.

"This popular life of the great Swiss naturalist puts before us not
only a profound thinker and an indefatigable worker, but a most loveable
character.
The book is pleasantly and simply written, and there
is nothing that for a moment draws the reader's attention from the sub-
ject."-Pall Mall Gazette.

G. P. PUTNAM'S SONS, NEW YORK AND LONDON

Leaders in Science