Proceedings of the Linnean Society of London - University Library

24 PI10CEEDING8 Ol' THE
Another pertinent question is as to whether or not Linnaeus may
be considered to have materially contributed to the discovei'y of
sexuality in plants. In his prize essay, the ' Disquisitio de Sexu
Plantarum ' (J 760) he says that it is very difficult to say who first
made this discovery. Ear iVoni laying any claim to it himself, he
mentions Millington, Grew, Kay, Camerarius, and Vailhint as
moderns who had more or less clearly stated it. What still remained
to be determined was the mode of impregnation. That it is
attributable to the pollen was no longer a matter of doubt.
Vaillant (1718) had expressed the opinion that it was effected by
the transmission to the ovules, not of any material substance, but
of a volatile essence exhaled by the pollen-grains. On the other
hand, Morlaud (Phil. Trans. 1704) asserted that the pollen-grains
pass bodily down the style into the ovules, there giving rise to
embryos. Needham, in his 'Microscopical Discoveries' (1745),
pointed out that it is impossible for the pollen-grains to reach the
ovary, and asserted that the farina, falling on the heads of the pistil,
dissolves in the papillaD, and the subtlest of its ])arts only penetrates
into the tubes leading to the ovary. The chief contribution
made by Linnams is contained in the dissertation ' Sponsalia
Plantarum ' (174G : Amoon. Acad, i.), where it is clearly laid down
that the pollen-grains of plants correspond to the spermatozoa of
animals, an inaccurate statement and yet an approach to the truth.
Like JVeedham, Linnaais denied that the pollen-grains descend
into the ovary, rightly stating that they remain on the stigma,
where, he thought, they burst and set free their contents, which
penetrate to and fertilize the ovules (cf. ' General io ambigena,'
Amoon. Acad. vi.). This is an advance, but not a considerable
advance. At the same time it must be recognized that by his general
treatment of the subject he established the theory of sexuality
upon a sounder basis and in a clearer light than did any of his
predecessors.
We come now to the consideration of a more debatable matter
the share of Linnanis in the progress of Plant-Moi*phology, the
side of botanical science that regards the parts of plants in the
abstract, that considers them from the point of view of tbeir
develo|)ment and nuilual relations rather than from that of their
lunclious, that determines their homologies rather than their
analogies. Without going far buck into ancient history, it may
be stated that the foundation ol' modern plant-morphology was
laid by Joachim Jung in his remarkable \\ orks, the ' Doxoscopia,'
tirst published in 1()(32, and tlu> ' Isagoge Phytoscopica,' first
publislied in I 67!K Li these works are to be found a clear analysis
ol' the plant-body iuto its constituent members, a description of
the members witii a precise nomenclature, and a recognition of
the essential similarity between the foliage and tloral leaves.
Although the works of Jung were not much quoted by Linnaeus,
yet, as we know, they were included in his library, and, moreover,
the id(>as and terminology of Jung were fully set out in the first
volume of Kay's ' ilistoria Plantarum,' a work with which Linu»us
was familiar. In these circumstances there can be little doubt
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