the body, as the shell, outer protective structures, the limbs,
mouth-parts, antennae, etc., are first affected by the causes which
produce variation, while he distinctly states that it requires a longer
time for variations to take place in the internal organs. On the latter
he relied in defining his classes.

One is curious to know how Lamarck viewed the question of species. This
is discussed at length by him in his general essays, which are
reproduced farther on in this biography, but his definition of what a
species is far surpasses in breadth and terseness, and better satisfies
the views now prevailing, than that of any other author.

His definition of a species is as follows:

"Every collection of similar individuals, perpetuated by generation
in the same condition, so long as the circumstances of their
situation do not change enough to produce variations in their
habits, character, and form."

Lamarck's rare skill, thoroughness, and acuteness as an observer,
combined with great breadth of view, were also supplemented by the
advantages arising from residence in Paris, and his connection with the
Museum of Natural History. Paris was in the opening years of the
nineteenth century the chief centre of biological science. France having
convalesced from the intestinal disorders of the Revolution, and, as the
result of her foreign wars, adding to her territory and power, had begun
with the strength of a young giant to send out those splendid exploring
expeditions which gathered in collections in natural history from all
parts of the known or accessible world, and poured them, as it were,
into the laps of the professors of the Jardin des Plantes. The shelves
and cases of the galleries fairly groaned with the weight of the
zooelogical riches which crowded them. From the year 1800 to 1832 the
French government showed the greatest activity in sending out exploring
expeditions to Egypt, Africa, and the tropics.[119]

The zooelogists who explored Egypt were Geoffroy St. Hilaire and Savigny.
Those who visited the East, the South Seas, the East Indian archipelago,
and other regions were Bruguiere, Olivier, Bory de St. Vincent, Peron,
Lesueur, Quoy, Gaimard, Le Vaillant, Edoux, and Souleyet. The natural
result was the enormous collections of the Jardin des Plantes, and
consequently enlarged views regarding the number and distribution of
species, and their relation to their environment.

In Paris, about the time of L