in Organic and Inorganic Bodies. 369 



style to the ovula, but rather whether even actual contact of 

 these particles with the surface of the stigma were necessary to 

 impregnation. 



Finally, it may be remarked, that those cases already adverted 

 to, in which the apex of the nucleus of the ovulum, the sup- 

 posed point of impregnation, is never brought into contact with 

 the probable channels of fecundation, are more unfavourable to 

 the opinion of the transmission of the particles of the pollen to 

 the ovulum^ than to that which considers the direct action of 

 these particles as confined to the external parts of the female 

 organ. 



The observations, of which I have now given a brief account, 

 were made in the months of June, July, and August, 1827. 

 Those relating merely to the form and motion of the peculiar 

 particles of the pollen were stated, and several of the objects 

 shown, during these months, to many of my friends, particularly 

 to Messrs Bauer and Bicheno, Dr Bostock, Dr Fitton, Mr E. 

 Forster, Dr Henderson, Sir Everard Home, Captain Home, Dr 

 Horsfield, Mr Koenig, M. Lagasca, Mr Lindley, Dr Maton, 

 Mr Menzies, Dr Prout, Mr Renourd, Dr Roget, Mr Stokes, 

 and Dr Wollaston ; and the general existence of the active mole- 

 cules in inorganic as well as organic bodies, their apparent inde- 

 structibility by heat ; and several of the facts respecting the 

 primary combinations of the molecules, were communicated to 

 Dr Wollaston and Mr Stokes in the last week of August. 



None of these gentlemen are here appealed to for the correct- 

 ness of any of the statements made ; my sole object in citing 

 them being to prove from the period and general extent of the 

 communication, that my observations were made within the dates 

 given in the title of the present summary. 



The facts ascertained respecting the motion of the particles of 

 the pollen, were never considered by me as wholly original; 

 this motion having, as I knew, been obscurely seen by Need- 

 ham, and distinctly by Gleichen, who not only observed the mo- 

 tion of the particles in water after the bursting of the pollen, 

 but in several cases remarked their change of place within the 

 entire grain. He has not, however, given any satisfactory ac- 

 count either of the forms or of the motions of these particles, 

 and in some cases appears to have confounded them with the 

 elementary molecule, whose existence he was not aware of. 



JULY SEPTEMBER 1828. A a 



