, p. 335).

[155] The subject of protective mimicry is more explicitly stated by
Dr. Darwin in his earlier book, _The Loves of the Plants_, and, as
Krause states, though Roesel von Rosenhof in his _Insekten-Belustigungen_
(Nurnberg, 1746) describes the resemblance which geometric caterpillars,
and also certain moths when in repose, present to dry twigs, and thus
conceal themselves, "this group of phenomena seems to have been first
regarded from a more general point of view by Dr. Darwin."

[156] _Zoonomia_, vol. i., p. 170.

[157] Mr. Samuel Butler, in his _Evolution, Old and New_, taking it for
granted that Lamarck was "a partisan of immutability till 1801,"
intimates that "the secret of this sudden conversion must be found in a
French translation by M. Deleuze of Dr. Darwin's poem, _The Loves of the
Plants_, which appeared in 1800. Lamarck--the most eminent botanist of
his time--was sure to have heard of and seen this, and would probably
know the translator, who would be able to give him a fair idea of the
_Zoonomia_" (p. 258).

But this notion seems disproved by the fact that Lamarck delivered his
famous lecture, published in 1801, during the last of April or in the
first half of May, 1800. The views then presented must have been formed
in his mind at least for some time--perhaps a year or more--previous,
and were the result of no sudden inspiration, least of all from any
information given him by Deleuze, whom he probably never met. If Lamarck
had actually seen and read the _Zoonomia_ he would have been manly
enough to have given him credit for any novel ideas. Besides that, as we
have already seen, the internal evidence shows that Lamarck's views were
in some important points entirely different from those of Erasmus
Darwin, and were conceptions original with the French zooelogist.

Krause in his excellent essay on the scientific works of Erasmus Darwin
(1879) refers to Lamarck as "evidently a disciple of Darwin," stating
that Lamarck worked out "in all directions" Erasmus Darwin's principles
of "will and active efforts" (p. 212).

CHAPTER XV

WHEN DID LAMARCK CHANGE HIS VIEWS REGARDING THE MUTABILITY OF SPECIES?

Lamarck's mind was essentially philosophical. He was given to inquiring
into the causes and origin of things. When thirty-two years old he wrote
his "Researches on the Causes of the Principal Physical Facts," though
this work did not appear from the press until 1794, when he was fifty
years