t number, and the work went
steadily forward to completion in 1839. It was called by the great
naturalist, Cuvier, "the most magnificent monument that art ever raised
to ornithology." It contained 448 beautifully colored plates, showing
1065 species of North American birds, each of them life size.

Before it was completed, Audubon had planned another work on similar
lines, to be known as "The Quadrupeds of America," and set to work at
once to gather the necessary material, which meant the study from life
of each of these animals. He even projected an extensive trip to the
Rocky Mountains in search of material, but was pursuaded by his friends
to give it up, as he was then nearly sixty years of age, and suffering
from the effects of his long years of exposure. His sons assisted him in
the preparation of the work, the first volume of which appeared in 1846,
the last in 1854, three years after his death.

Audubon's life illustrates strikingly the compelling power of devotion
to an ideal. Few men have met such discouragements as he, and fewer
still have overcome them. For many years, in all climates, in all
weathers, pausing at no difficulty or peril, his life frequently
endangered by wild beasts or still wilder savages, he trudged the
pathless wilderness, quite alone, sleeping under a rude shelter of
boughs or in a hollow tree, living on such game as he could shoot,
seeking only one thing, new birds, and when he found them, observing
their habits and setting them on paper with an infinite patience. On one
occasion, rats got into the room where his drawings were stored, and
destroyed almost all of them; but he set to work at once re-drawing
them, where most men would have given up in despair. His work remains to
this day the standard one on American birds--a mighty monument to the
ideals of its maker.

[Illustration: AGASSIZ]

Jean Louis Rudolphe Agassiz was also a born naturalist, but no such
obstacles confronted him as Audubon surmounted, nor did he strike out
for himself a field so absolutely original. Born in Switzerland in 1807,
the descendent of six generations of preachers, but destined for the
profession of medicine, he refused to be anything but a naturalist. From
his earliest years, he showed a passion for gathering specimens, and his
first collection of fishes was made when he was ten years old. He
received the very best training to be had in Switzerland, France and
Germany, and early attracted attention for