mingled astonishment, delight, and bewilderment of the closet
naturalists. The followers of Linnaeus in the "golden age of
natural history," a few decades before, had increased the number
of known species of fishes to about four hundred, of birds to one
thousand, of insects to three thousand, and of plants to ten
thousand. But now these sudden accessions from new territories
doubled the figure for plants, tripled it for fish and birds, and
brought the number of described insects above twenty thousand.
Naturally enough, this wealth of new material was sorely puzzling
to the classifiers. The more discerning began to see that the
artificial system of Linnaeus, wonderful and useful as it had
been, must be advanced upon before the new material could be
satisfactorily disposed of. The way to a more natural system,
based on less arbitrary signs, had been pointed out by Jussieu in
botany, but the zoologists were not prepared to make headway
towards such a system until they should gain a wider
understanding of the organisms with which they had to deal
through comprehensive studies of anatomy. Such studies of
individual forms in their relations to the entire scale of
organic beings were pursued in these last decades of the century,
but though two or three most important generalizations were
achieved (notably Kaspar Wolff's conception of the cell as the
basis of organic life, and Goethe's all-important doctrine of
metamorphosis of parts), yet, as a whole, the work of the
anatomists of the period was germinative rather than
fruit-bearing. Bichat's volumes, telling of the recognition of
the fundamental tissues of the body, did not begin to appear till
the last year of the century. The announcement by Cuvier of the
doctrine of correlation of parts bears the same date, but in
general the studies of this great naturalist, which in due time