to the
right conduct of the organism, but the precise nature of its operations
remains inscrutable. The vast importance of the operations of these
intermediate organs is unquestioned.

A consideration of the functions of that other set of organs known
collectively as the nervous system is reserved for a later chapter.

VI. THEORIES OF ORGANIC EVOLUTION

GOETHE AND THE METAMORPHOSIS OF PARTS

When Coleridge said of Humphry Davy that he might have been the greatest
poet of his time had he not chosen rather to be the greatest chemist, it
is possible that the enthusiasm of the friend outweighed the caution of
the critic. But however that may be, it is beyond dispute that the man
who actually was the greatest poet of that time might easily have taken
the very highest rank as a scientist had not the muse distracted his
attention. Indeed, despite these distractions, Johann Wolfgang von
Goethe achieved successes in the field of pure science that would insure
permanent recognition for his name had he never written a stanza of
poetry. Such is the versatility that marks the highest genius.

It was in 1790 that Goethe published the work that laid the foundations
of his scientific reputation--the work on the Metamorphoses of Plants,
in which he advanced the novel doctrine that all parts of the flower are
modified or metamorphosed leaves.

"Every one who observes the growth of plants, even superficially,"
wrote Goethe, "will notice that certain external parts of them become
transformed at times and go over into the forms of the contiguous parts,
now completely, now to a greater or less degree. Thus, for example, the
single flower is transformed into a double one when, instead of stamens,
petals are developed, which are either exactly like the other petals of
the corolla in form, and color or else still bear visible signs of their
origin.

"When we observe that it is possible for a plant in this way to take a
step backward, we shall give so much the more heed to the regular course
of nature and learn the laws of transformation according to which she
produces one part through another, and displays the most varying forms
through the modification of one single organ.

"Let us first direct our attention to the plant at the moment when it
develops out of the seed-kernel. The first organs of its upward
growth are known by the name of cotyledons; they have also been called
seed-leaves.

"They often appear shapeless, filled w