The Scientific Revolution

Lesson 7: The life sciences in the later seventeenth century

Botany

The microscope also revolutionized plant science, enabling much closer observation and the discovery of previously unknown parts of plants. The discovery of the circulation of the blood in animals led Johann Daniel Major in 1660 to propose that sap circulated in plants, an idea that led to a great deal of research.

The rise of the mechanical philosophy led to the desire to explain the processes within plants in mechanical terms. Robert Hooke included observations of vegetable matter in his Micrographia (1665). His observations of the pores in cork led him to make the first description of “cells” in plants.

As so often happened, Hooke’s initial observation was fully developed by others, notably Nehemiah Grew and Marcello Malpighi, who established the universality of cellular structure. The Royal Academy of Sciences largely avoided microscopy; their favored method of plant analysis was chemical distillation.

The results proved confusing and hard to interpret but the Academy was reluctant to abandon it, as members believed that distillation would provide clues to the nutritional values and medicinal uses of plants.

The major problem of plant scientists in the late seventeenth century was to assimilate the flood of botanical information, dried plant specimens, seeds, and living plants pouring into Europe from all over the world. There were several projects to systematize descriptions of plants into vast and theoretically exhaustive catalogs.

The Englishman John Ray, the Swede Olof Rudbeck, and the Royal Academy of Sciences all began universal plant compendia. All these efforts failed, dogged by bad luck, as in the fire that destroyed much of Rudbeck’s work or the shifts in government policy to which the Academy was vulnerable, but also stymied by the sheer vastness of the task.

Ray came closest to success, with the three installments of his History of Plants in 1682, 1688, and 1704 dealing with nineteen thousand plants. Ray also had the most sophisticated classification scheme, set forth in Botanical Method (1682), which introduced the concept of “species”.

Building on ancient and modern predecessors, Ray attempted to distinguish between the essential and accidental characteristics of plants, and warned against basing classification on only one or two factors. (Ray also wrote about science and religion, as can be seen from document 10.3 of Oster.)

Ray’s contemporary Joseph Pitton de Tournefort (1656-1708), Professor of Botany at the Royal Botanical Garden of France and the leading French botanist of his time introduced a classification scheme based on genus rather than species, but had less success than Ray.

The German Rudolf Jacob Camerer (1665-1721), known by the Latinization Camerarius, first demonstrated plants’ sexual nature. Camerarius was a medical professor and director of the Botanical Garden at the University of Tubingen.

The question of whether plants reproduced sexually had been asked since Aristotle and Theophrastus. Grew and Ray supported plants’s sexual reproduction, but were unable to demonstrate it. Camerarius settled the question by establishing the fertilising role of pollen through experiment. It took longer for his discoveries to reach other botanists due to the 1694 publication of his Letter on the sex of plants in an obscure journal.

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