SEXUALITY IN PLANTS—JOHNSON. 385 
Grew’s work by Rudolph Jakob Camerarius, of Tiibingen. Came- 
rarius fully appreciated the presence of areal problem here. He also 
had the genius to see that the philosophical attempts of many of his 
immediate predecessors to discover its solution entirely in their own 
inner consciousnesses were futile. With the insight of a modern 
experimenter Camerarius put the question to the plants themselves. 
The results of his experiments, as reported in the famous letter of 1694 
to Prof. Valentin, of Giessen, were clear and conclusive. After noting 
that the aborted seeds were produced by isolated—and therefore 
unpollinated—female plants of Mercurialis, and of mulberry, by 
castrated plants of the castor bean, and by plants of Indian corn from 
which he had removed the stigmas, Camerarius gives his interpreta- 
tion of these phenomena. He says (Ostwald ‘ Klassiker,” p. 25): 
Tn the vegetable kingdom. there is accomplished no reproduction by seeds, that 
most perfect gift of nature, and the usual means of perpetuating the species, unless 
the previously appearing apices of the flower have already prepared the plant therefor. 
It appears reasonable to attribute to these anthers a nobler name and the office of 
male sexual organs. 
In the 70 years after Camerarius had proved in this way the existence 
of two sexes, and the fertilizing function of the pollen in plants, 
little advance was made. Bradley, of London, Gleditsch, of Berlin, 
and Gov. Logan, of Pennsylvania, confirmed parts of Camerarius’s 
work, and the great Linnzeus accepted the conception of the stamens 
and pistils as sexual organs as clearly proven, not, be it noted, by the 
results of Camerarius’s experiments, but by the “nature of plants.” 
In 1761 J. G. Koelreuter, of Carlsruhe, published an account of the 
first systematic attempt that had been made, with either plants or 
animals, to produce and carefully study artificial hybrids. In his 
work with hybrid tobaccos, he demonstrated that characters from 
both parents are often associated in a single offspring. He thus not 
only completed Camerarius’s work, but also, by showing that the male 
parent participates in the makeup of the offspring, he helped mate- 
rially to break down the “emboitement theory” of Christian Wolff, 
which assumed that the embryo came entirely from the egg, and that 
its characters could not be influenced by the male parent. It is true 
that Koelreuter was mistaken in believing that fertilization is accom- 
plished by the mingling of the oil on the pollen grains with the secre- 
tion of the stigma to form a mixed fluid, which he supposed then 
penetrated to the ovule. Nevertheless, his conception of the mingling 
of two substances was a move with the proper trend. 
Koelreuter also demonstrated that in nature the pollen necessary 
to fertilization is often brought to the stigma by insects. He thus 
opened up a field of research which was cultivated with such splendid 
effect by Konrad Sprengel 30 years later, and by Darwin, Miller, and 
others a century afterwards. 
73176°—sM 191425 
