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Camerarius tested his pollen- catching hypothesis for the silk by removing it from two
of the cobs soon after they appeared, and noted that no fertile seeds formed in the ear as a
result:I carefully cut off the stigmas [“silk”] of maize that were already dependent, in conse-
quence of which the two cobs remained entirely without seeds, though the number of
abortive seed capsules was very great.^54The crucial experiment, however, was to deprive an intact cob of pollen by removing
the stamens and observing the effect on kernel production. In maize, it is easy to remove
all the stamens of a plant at once by cutting off the entire tassel before it matures. When
Camerarius performed the experiment on isolated plants, the results were dramatic:when the unfolding tassels were cut away before they could open, two cobs appeared
that were devoid of any seed, containing a great number of empty seed- capsules
instead.^55However, Camerarius conscientiously reported that a third cob contained eleven fertile
seeds, despite the absence of tassels. Thus, as in the case of Cannabis, the results with maize
were less than definitive. Although eliminating the male flowers resulted in sterile seeds in
the vast majority of cases, the presence of a smaller number of fertile seeds in Cannabis and
maize appeared to contradict the sexual theory. Summoning courage once again from the
example and words of Robert Boyle, Camerarius, refused to despair:It is not, however, the case that I should lose hope even if certain experiments may
have continually failed to respond to my desires, given that there is a philosopher
reminding me that I have numerous comrades who have shared this same fate.^56Indeed, a few years later, in 1698, Camererius discovered the likely cause of the
unexpected and unwanted fertile seeds in his experiments with Cannabis and maize,
which he published in the Ephemerides.^57 He observed that the female plants of spin-
ach, nettle, and other dioecious species occasionally produced either male or her-
maphroditic f lowers. The rare production of a few male or hermaphroditic f lowers
among Camerarius’s “female” Cannabis plants could well account for the presence of
the fertile seeds.^58 Similarly, hermaphroditic f lowers occasionally occur in both the
tassels and the ears of monoecious maize, which would allow the production of seeds
even in plants whose tassels had been removed.^59 As we shall see in later chapters,
eighteenth- and nineteenth- century critics of the Epistola, apparently unaware of his
1698 paper, continued to argue that the presence of even a small number of fertile
seeds in Camerarius’s emasculated Cannabis and maize plants constituted proof that
the sexual theory was false.
Although being completely forthcoming about results that did not agree with his
hypothesis, Camerarius nevertheless concluded that the sexual theory was supported by the
vast majority of his data. His summary of the sexual theory was therefore the first straight-
forward formulation of the two- sex model of plants: