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PART I. | . HISTORICAL INTRODUCTION. 27 
by experiment, partly by specifying the sexual organs in various forms of 
flowers ; while on the other hand Tournefort! and Pontedera® tried to prove 
that these views were untenable, chiefly from philosophical considerations. 
The contest may be considered to have been settled in its main point by the 
masterly collection of proofs of the sexuality of plants given by Linneus 
in 1735.3 
After it had been shown that pollination is an essential condition for the 
production of seed, it still remained to show how the pollen-grains are con- 
veyed to the stigma ; and attempts were made to elucidate this also, but with 
less success. It was of course seen that in diclinic plants some external agency 
must convey the pollen-grains from the male to the female flowers, and the 
whole effect was ascribed to the wind ; in hermaphrodite flowers, on the other 
hand, it was supposed that the stigma is dusted with pollen from the same 
flower without the cooperation of any external agency. This had to take place 
either by the anthers and stigma coming in contact, or by the pollen falling 
down upon the stigma: the former would have to take place either before the 
flower opened, or by movements of the reproductive organs‘ ; to explain the 
latter, it was laid down as a general rule that those flowers whose stamens 
overtop the style have an erect position, and that those in which the style 
overtops the stamens are pendulous.> Meanwhile, since it was observed that 
many flowers contain honey and are visited by insects, the idea arose that these 
must be of some use in fertilisation. It was, however, supposed that in their 
visits they simply shake pollen from the anthers,® and not that they carry 
pollen from one flower to another. The importance and in many cases the 
necessity of the action of insects was not at all recognised,’ either in general 
or in any single case, if we except the observation of the fertilisation of Ficus 
earica by Chalcis Psenes (Ficus in Amen. Acad. i.). 
This last. observation stood for a long time isolated, until in 1761 Joseph 
Gottlieb Koelreuter demonstrated the necessity of insects’ aid in several 
other cases, such as Cucurbitacee, Iridee, Sambucus, and Viscum.’ This 
illustrious man remarked also, that in Malvaceae, Epilobium, and Pole- 
monium (Vorliuf. Nachr. p. 34), self-fertilisation is prevented by maturation 
of the reproductive organs at different times, and that in these plants the 
pistil of an older flower is fertilised by the aid of insects with pollen from a 
younger flower.’ In the case of most plants, however, he held to the old 
1 Institutiones rei herbaric (Paris: 1700). 
2 Anthologia, seu de floris naturd (Patav. : 1720). 
3 Fundamenta botanica (Amsterdam : 1735). 
4 It was Vaillant who first observed this phenomenon. For the meaning which 
was assigned to it, see Linneus, De nuptiis et seaw plantarum, 1729, first printed in 
1829; and ‘* Sponsalia Plantarum,” p. 46, in Amenitates Academice, i. 
5 Linneus, loc. cit. and “‘ De economid Nature,” in Amen. Acad. i. 
6 « Sponsalia Plantarum” and ‘‘ De nectariis forum,” Amen. Acad. iv. 
7 See, for instance, the explanation of the act of fertilisation in Viola tricolor in 
** Sponsalia Plantarum,” p. 37. : 
8 Vorléufige Nachricht von cinigen das Geschlecht der Phlanzn betreffenden Versuchen 
und Beobachtungen (Leipzig: 1761), and Fortsetzung der vorliufigen Nachricht 
(Leipzig : 1763). 
After showing how well the organisation of these plants is fitted for crossing 
Koelreuter remarks: ‘‘ An id aliquid im recessu habeat, quod hujuscemodi flores 
numquam proprio suo pulvere, sed semper eo aliarum sue speciei impregnentur 
merito queritur. Certe natura nil facit frustra.” 
