And this Doctrine, more recently yet, the learned Alston has endeavoured to overturn. 



* 



LinnEeus's direct experiment in this Essay proves the fallacy here. Of the Hop, he says, " that the female produces its cones of flowers 

 equally well when separated from the male plant, as Tournefort found in the Royal Gardens of Paris." This arose from the cone of the hop 

 being 2i calyx, which grows equally in both instances; but the seeds so produced have not been found to vegetate. 



The reader now sees upon what flimsy ground the opposition to the sexes of plants is founded, and is enabled to form his own conclusion, 

 as to the truth of this doctrine, so admirably confirmed as it has been by LINNtEUS. 



Linnffius, in the Hortus ClifFortiauus, page 441, however, does his opponent ample justice as an accurate botanist. " Clarissimus Pon. 

 TED ERA, qui oculatissimus est auctor, et in examinando flores nulll inferior." 



* The arguments against the sexes of plants, very similar to those of Pontedera, are collected by the ingenious Professor Alston, in his 

 " Tyrocinium Botanicum," and in a Dissertation on the Sexes of Plants, to be found in the first volume of the " Edinburgh Physical and 

 Literary Essays." In page 250 of that essay, Alston says, " I shall pass a variety of later authors who have treated on this subject ; and 

 come to the most strenuous defender of the sexes of plants, who has collected all the arguments for it that perhaps can be advanced, and pre- 

 tends to have demonstrated it fully: I mean the famous and very learned Carolus Linnaeus, professor of medicine and botany m the university 

 of Upsal, fellow of a great many philosophical societies ; and certainly one of the greatest botanists of this age. For this great man thus 

 writes: " Antheras et stigmata constituere sexum plantarum, a palmicolis, MiUingtono, Grewio, Rayo. Camerario, Godofredo, Morlando, 

 Vaillantio, Blairio, Jussievio, Bradleyo, Royeno, Logano, &c. detectum, descriptum, et pro infallibili assumptum : Nee uUum, apertis 

 oculis considerantem cujuscunque plantae flores, latere protest ; quod demonstratum in Sponsalibus Plantarum, Upsalrae 1746, in 4to.' And 

 elsewhere, " Generationem vegetabilium fieri, mediante poUinis antherarum illapsu supra stigmata nuda, quo rumpitur pollen, efllatque auram 

 seminalem, quee absorbetur ab humore stigmatis ; quod confirmat oculus, proportio, locus, tempus, pluviae, palmicolffi, flores nutantes, sub- 

 mersi, syngenesia; immo omnium florum genuina consideratio." 



" Yet I cannot help thinking this doctrine not capable of demonstration, far less that the genuina consideratio of any flower can make 

 it probable : Camerarius himself doubted of it ; Tournefort disbelieved it ; and Pontedera uses many arguments to refute it." 



In order to do away all belief in the sexes of plants, he relates the following experiments. 



1. "In the spring 17 37, I transplanted three sets of the common Spinage, long before it could be known whether they were flowering 

 or seed-bearing plants, from a little bed on which they were raised, into a place of the garden, full eighty yards distant, and almost directly 

 south ; there being two hawthorn and three holly hedges, all pretty thick and tall, between them and their seed-bed ; and no other spinage 

 in the garden, nor so near them by far : all the three proved fertile plants, and ripened plenty of seeds. I sowed them ; they grew and 

 prospered as well as any spinage-seed possibly could do. This, I own, made me at first call in question the sexes of plants, which 1 formerly 



too implicitly believed. 



2. " The same year, a few plants of the common hemp, which I had raised for a specimen from the seed, being accidentally destroyed 

 when very young; and finding afterwards, about the end of June, a pretty strong but late plant of Hemp, growing in the inclosure to the 

 east of Holyrood-house, commonly called the Bowling-green, by itself: I caused great care to be taken of it, there not being that year any 

 hemp raised within a mile of it, that I could find. This plant grew luxuriantly; and, though bad weather in the autumn made me pluck it 

 up a little too soon, yet I got about thirty good seeds from it, which the succeeding spring produced as thriving male and female plants, as 

 if the mother-hemp had stood surrounded with males. And, 



3. " In the spring 1741, I carried two young seedling plants of the French Mercury, long before there was any in flower, from the city 

 physic-garden, the only place where it was then to be found in this country, to the king's garden at the Abbey; which are more than seven 

 hundred yards distant from one another, with many high houses, trees, hedges, and part of a hill between them : and planted one of them 

 in one inclosure, where it was shaded from the sun the greatest part of the day; and the other, in another, twenty-five yards distant, exposed 

 to the south and west. Both plants ripened fertile seeds ; and the last shed them so plentifully, that it proved a troublesome weed for several 

 years, though none of the species was to be found in that garden, for more than twenty years preceding." 



In answer to such stubborn facts, it were to be wished, that the learned professor had continued from year to year these experiments, 

 and multiplied them, and under different circumstances, and then he would have fixed conviction on the mind. As the case now stands, 

 these experiments are contradicted by the experiments of Millar recorded in his Dictionary, under article Generation, also by those of Lin- 

 naeus in this Essay. 



His experiments on the Spinach and Dogs Mercury, (of the Hemp we shall speak when we come to Linnseus's experiment on that 

 plant), were either defective as not being made sufficiently apart for the winds, or insects, to perform the office of bridegroom; or, as later 

 observers remark, that even on Pistilliferous plants, males will occasionally appear, especially in the Spinach, and hence the fallacy of the 

 experiments, when they turn out contrary to the Sexes of Plants. 



Speaking of the Spinach, Baron De Gleichen, in his " Observations Microscopiques," says, " J'ai aussi fait avec cette plante 1' expe- 

 rience ordinaire, en 6tant les plantes males, pour empecher les plantes femelles d'etre fecondees. Dans ce dessein j'ai pris environ quarante 

 grains de la semence herissee, et au lieu de les semer, je les ai mis en terre en rang piece per piece separement, dans une distance asses con- 

 siderable I'un de I'autre. Aussitot que je decouvris une plante male, je I'arrachai, et I'ecartai, jusqu'a ce que mes plantes furent enfin reduites 

 au nombre de douze, des quelles je fus bien assure, que ce n'etoit que des femelles. Je visitai bien souvent ces plantes, et j'ouvris de terns en 

 tems quelques oeufs seminaux, que j'examinai a I'aide du Microscope, et que je trouvai premierement tons vuides, et bientot apres tous fc- 

 condes. Aussitot je visitai mes plantes encore une fois bien soigneusement pour voir, s'il n'y avoit pas parmi cllcs quelque amant cache. Mais 

 sans decouvrir une seule plante male, je fus bien surpris de voir, que presque la moitie de mes plantes etoient des Hermaphrodites, dont les 

 vaisseaux de la poussiere avoient pousse en grand nombre entre les fleurs femelles. J'ordonnai d'abord a mon jardinier de chercher sur une 

 grande couche d'un autre jardin, semee d'epinars, s'il y trouveroit plus.de ces Hermaphrodites, et elles ne manquerent pas la non plus, et pro- 

 duirent de la semence meure, aussi bien que celles-la. Je la cueillis soigneusement, la semai I'annee suivante et j'en retirai en plus grande 

 partie des Diphytes avec quelques Hermaphrodites. J'aurois fait plutot cette decouverte, et par la je me serois dispense de faire une experience 

 superflue, si je n'avois pas ignore alors, ce que j'ai lu dans la suite dans la remarque a la Planche XL. de I'oeuvre de Biakwell; savoir que 

 Camerarius avoit trouve plus d\me fois, mais pourtant pas trop souvent, des Hermaphrodites parmi les plantes d'Epinars. Cependant 

 cette nouvelle experience sert a nous rendre plus attentifs, et a nous dessiler les yeux dans des pareils essais. Mr. Moller, qui s'est avise de 

 combattre le Systeme de fecondation, en appellant aussi a la semence feconde, qu'il avoit obtenuc d'une seule plante d'Epinars trouvee par 

 hazard parmi les plantes de pastenade, n'auroit pas eu cette vaine joye, s'il avoit examine cette plante plus souvent et avec plus d'attention. 



*o' * que 



