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another abortive attempt on his life. This time, after a period of convalescence, he regained
his momentum and went on to make significant contributions to plant biology.
Schleiden is chiefly remembered as the co- founder of the cell theory in biology, along
with zoologist Theodore Schwann. In opposition to Kant, he believed that biology was
equal to chemistry and physics as a science, and he was contemptuous of all vitalist theories.
In Principles of Scientific Botany: Botany as an Inductive Science (1849), regarded as the first
modern textbook of plant biology, Schleiden blamed Goethe and the nature philosophers
for promoting the notion that “a poetic treatment of nature could be placed on a level with,
or even preferred to, strictly scientific approaches”:The unfortunate seed which Goethe sowed, sprang up with sad rapidity; and ... we
owe it to him that, in Botany, whims of the imagination have taken the place of ear-
nest and acute scientific investigation. In that unbounded region every individual’s
imagination had naturally equal right; there was a total want of any scientific princi-
ple which should undertake the decision between differing opinions of any method.^4Schleiden blamed Goethe and the nature philosophers for botany’s backwardness as a
science compared to zoology. No doubt Schleiden’s words were music to the ears of the
science faculties at Jena and other German universities, who had chafed in silence during
the mercurial reign of the great genius. Yet despite Schleiden’s reputation as a champion
of the scientific method, he has the dubious distinction of being the last botanist to dis-
pute the sexual theory. In this regard he was, ironically, Goethe’s scientific heir.
To fully appreciate the rationale behind Schleiden’s radical reinterpretation of pollina-
tion, it is necessary to return to the immediate aftermath of August Henschell’s provocative
book, On the Sexuality of Plants, which challenged the findings of Koelreuter.Hybridize, Win a Prize: The Vindication of Koelreuter
Goethe had lived long enough to see Henschell’s critique of Koelreuter’s experiments
refuted by A. F. Wiegmann, a physician from Braunschweig. In 1822, the Royal Prussian
Academy of Sciences offered a prize for a resolution of the question of whether plants could
form hybrids. Since hybrid formation was central to the sexual theory, the unspoken aim of
the prize was to obtain unequivocal evidence for sex in plants.
As a boy of sixteen, Wiegmann had crossed different species of geraniums and had suc-
ceeded in producing two different hybrids. Later, he continued his observations of plants
while maintaining a medical practice, but he didn’t initiate serious hybridization studies
until the Prussian prize was announced. Four years later, in 1826, the Prussian Academy
awarded him the prize for confirming Koelreuter’s results, although they granted him only
half of the prize money because he had not, in their collective opinion, conclusively dem-
onstrated that his putative hybrids were actual hybrids. However, to do so would have
been a tall order, given the absence of any methods for quantifying maternal and paternal
contributions to hybrid progeny. Gregor Mendel’s studies of inheritance in peas were still
several decades away and, in any event, did not become widely known until the turn of the
centur y.