i
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The Difficult Birth of the Two- Sex Model
By the mid- seventeenth century, the transition from natural philosophy to exper-
imental natural philosophy, referred to as the “Scientific Revolution,” was in full swing.
A century earlier, Copernicus, Galileo, and Vesalius had overturned venerable Greek notions
about cosmology, mechanics, and human anatomy. Then, in 1620, in his magisterial treatise
Novum Organum Scientiarum (New Instrument of Science), Francis Bacon espoused an
empirical approach to the study of nature based on observation and experiment, rather than
on the received wisdom of the past.^1 Bacon’s writings provided the impetus for the estab-
lishment of the Royal Society of London in 1660, the first public body devoted exclusively
to “the corporate pursuit of scientific research.”^2 Despite these early advances in the physi-
cal and medical sciences, however, botany remained mired in its medieval soil. Naturalists
like John Ray were primarily concerned with classification and showed little interest in the
mechanisms underlying plant growth and development. On such questions, Aristotle and
Theophrastus still served as the ultimate authorities.
The first inkling that Greek descriptions of plant anatomy were as inadequate as their
views on plant taxonomy followed swiftly in the wake of the invention of the microscope.
When trained on plant tissues for the first time, the microscope revealed a multitude of new
structures unknown to the Greeks, and while these discoveries helped free botanists from
the influence of their classical cicerones, they also raised questions about their functions.
Francis Bacon had argued that to elucidate a function, observations must be supplemented
with well- designed experiments.
The discovery of sex in plants through a combination of observation and experiment
was arguably the crowning achievement of seventeenth- century botany. It occurred in
three successive stages corresponding to the contributions of three outstanding physician-
botanists: Marcello Malpighi in Italy, Nehemiah Grew in England, and Rudolf Jacob
Camerarius in Germany. Malpighi’s and Grew’s studies were based entirely on microscope