82 Dr. H. Karsten on the Sexual Life of 



By the labours of Burkard, Morland, C. J. Geoffroy, Bradley, 

 Vaillant, Blair, and other observers, the sexual relations of plants 

 were in various ways so elucidated, that, to the methodical mind 

 of the great Swedish naturalist, and by means of his own nu- 

 merous and accurate observations, their proofs were complete 

 and multiplied. Indeed, he clearly proved that the female 

 plants of Cannabis sativa, when carefully protected from the 

 access of the pollen, produced no seeds. 



The views of Tournefort and Pontedera, based upon some 

 fallacious observations, respecting the importance and purpose 

 of the anthers, failed to invalidate the antagonistic facts adduced 

 by Linnaeus and Dillenius. 



The researches of Needham (1745) and Gleichen (1781) on 

 the structural relations between the pollen and stigma, as well as 

 the successful attempts of Kolreuter to generate bastard forms 

 by scattering the pollen of other plants on the stigma, contri- 

 buted most valuable support in favour of the doctrine of the 

 sexuality of plants. 



The inexact observations of F. J. Schelver and Henschel were 

 insufficient to cast a suspicion upon the results obtained by 

 Camerarius, Linnaeus, Kolreuter, and others. 



The hypothesis of the sexuality of plants entered on a new 

 stage as a consequence of the labours of the distinguished ana- 

 tomists of this century. The elongation of the pollen-cells was 

 first observed by Amici in 18.23; and Brongniart subsequently 

 witnessed, in several plants, the prolongation of tubes from the 

 pollen adherent to the stigma, and the extrusion of correspond- 

 ing tubules from the orifice (mouth) of the ovules. The latter 

 he presumed to be conducting tubes, through which the fructi- 

 fying contents of the pollen-tubes (for, like Needham, he imagined 

 that these tubes burst within the conducting tissue of the style) 

 were conveyed to the embryonic sac, discovered by Malpighi to 

 be present within the ovules. Amici followed the pollen-tubes, 

 as is illustrated by the communication presented by Mirbel, 

 from the pollen-corpuscle, through the conducting tissue (ob- 

 served by Malpighi, as early as 1675, in Monocotyledons) of the 

 canal of the style and of the embryo, to that little aperture in the 

 seed (discovered by Grew in 1671), the mouth of the ovule 

 (since named by Turpin the micropyle), into which this con- 

 scientious inquirer, moreover, saw it enter. This was confirma- 

 tory of the idea started by Samuel Morland (1703), that the 

 pollen descended through the style into the ovary, and there 

 entered the micropyle of the ovules. In this phenomenon we 

 also find the true explanation of the fact recorded by Richard 

 in 1811, that fibres grew from within the ovules of Blyxa 

 Auberti. 



