A. DeCandolle on the Life and Writings of Vaucher, 167 



trees ? In what way do they contribute to the fecundation of 

 the ovules ? Scarcely does one in a million of these grains 

 again pass from the ground by means of the wind or of insects 

 upon the stigma of a plant of the same species. The pollen 

 is so abundant, that the loss of a considerable proportion of 

 the grains does not hinder the species from being reproduced. 

 Thus the pollen which falls into the nectariferous tubes ofHel- 

 leborus foetidus is probably so much pollen lost, and the func- 

 tion of these secreting tubes has perhaps no connexion with 

 the rupture of the grains which fall into the liquid. Besides, 

 M.Vaucher adds, that it is not the same in Helleborus viridis, 

 and that its nectariferous tubes always appear closed. In short, 

 the author might have been asked how the grains of pollen, 

 bursting in the nectar of the tubes, could be transferred thence 

 to the stigma. The expression which he uses, " the stigmas 

 can hardly be fecundated but by the emanations of the necta- 

 ries," — does it indicate an action taking place at a distance, 

 an aura seminalis, setting out from the nectariferous tubes 

 where the grains of pollen are, and conducting something in- 

 visible to the stigmas ? This would seem to be so, according 

 to the words, but the idea of an aura seminalis is at the pre- 

 sent day inadmissible. We must suppose that this passage 

 relative to the Hellebore, with others containing analogous 

 expressions, were written by M. Vaucher a long time before 

 the modern discoveries of the pollinic tube and its penetration 

 into the stigma. It is the inevitable defect of so extended a 

 work not to be on a level with science on all points. An author 

 cannot be continually varying his plan and expressions in order 

 to follow the progress of discoveries. M. Vaucher quite ad- 

 mits, in several articles, the action of the pollinic tubes, but 

 his book was under preparation during a period of fifteen to 

 twenty years ! 



Let us proceed in seeking for proofs or presumptions in fa- 

 vour of the supposed action of the nectar. 



" In the genus Agrimonia the stamens, to the number of 

 fifteen, surround a small convex torus, which is velvety and 

 nectariferous ; the anthers have a very wide connective, and 

 bear upon the margins two turgid cells, which open princi- 

 pally towards the summit ; they are at first inclined on the 

 bottom of the flower, but at the time of flowering they raise 

 themselves up and spread ; afterwards, when they have lost 

 their pollen, their filaments fold themselves and form by their 

 union a kind of grating, and we see the connective impreg- 

 nate the pollen with the honeyed humour with which it is itself 

 covered, and afterwards the honeyed humour spread itself over 

 all the floral organs." I have in vain endeavoured to verify 



