Flora Unveiled

336 i Flora Unveiled

Grew realized that his theory was incomplete. In Swammerdam’s hermaphroditic snails,
fertilization was brought about in the usual way among animals— by copulation— with the
added feature of mutual penetration. But what went on in hermaphroditic flowers? Since
copulation between two flowers was clearly impossible, the only conceivable mechanism
seemed to be self- fertilization. Somehow, the “vegetable sperm” had to fertilize the young
fruit from the same flower so that viable seeds could form inside it. The discovery of the
pollen tube as the conduit for transmitting the sperm cells to the egg was still a long way off,
so Grew devised a plausible mechanism to account for fertilization. He invoked simple grav-
ity: the released pollen grains simply fell onto the “Uterus,” thus transmitting a “Prolifick
Virtue” to the ovary. To bolster his model, Grew resorted once again to animal analogies:

And that these Particles, only by falling down on the Uterus, should communicate

to it or to the sap therein, a Prolifick Virtue: it may seem the more credible, from the

manner wherein Coition is made in some Animals; as by many Birds, where there is

no Intromission, but only an Adosculation [impregnation by touching] of Parts: And

so in many Fishes. Neither in others, doth the Penis ever enter any further than the

Neck of the Womb.

But how could semen, which is a material substance, be transmitted to the interior of the
Womb by mere touch? To circumvent this difficulty, Grew proposed that semen in animals,
and “particles” in the case of plants, may only be the carrier of an invisible generative emana-
tion that readily passes through the walls of the Womb:

Nor doth perhaps the semen itself: or if it doth, it can by no means be thought, bodily

or as to its gross Substance, to enter the Membranes, in which every Conception, or

the Liquor intended for it, before any Coition, is involved; but only some subtle and

vivifick Effluvia, to which the visible Body of the Semen, is but the Vehicle. And the

like Effluvia may be easily transfused from the above said Particles into the Seed- Case

or Womb of a plant.^31

Nevertheless, Grew admitted that one should not press the animal analogy too far, for
“if anyone shall require the Similitude to hold in every Thing; he would not have a Plant to
resemble, but to be, an Animal.”
Whatever qualms Grew may have had about the reception his lecture would receive, they
appear to have been unfounded. By this time, Grew enjoyed a solid reputation, and Society
members honored him by enthusiastically endorsing the publication of his papers. Grew’s
new sexual theory was welcomed by his colleagues as a plausible, if unproven, hypothesis
about which little more could be said without experimental confirmation.
Support for the new sexual theory was slow in coming. The first published reference to
Grew’s hypothesis came ten years later, from his friend and fellow Society member, the
British naturalist John Ray. Ray is best known as the first to develop a classification scheme,
based on the concept of species, that was applicable to both plants and animals. In 1686,
in the first of his three- volume treatise Historia Plantarum, Ray quoted Grew’s descrip-
tion of the male sexual role of stamens approvingly. In support of Grew’s theory, Ray cited