in organic and inorganic Bodies. 171 



were transmitted through the stigma and 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 ad- 

 verted to, in which the apex of the nucleus of the ovulum, the 

 supposed point of impregnation, is never brought into contact 

 with the probable channels of fecundation, are more unfavour- 

 able 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 ac- 

 count, 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. Kcenig, M. Lagasca, 

 Mr. Lindley, Dr. Maton, Mr. Menzies, Dr. Prout, Mr. Re- 

 nouard, Dr. Roget, Mr. Stokes, and Dr. Wollaston ; and the 

 general existence of the active molecules in inorganic as well 

 as organic bodies, their apparent indestructibility 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 cor- 

 rectness 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 

 motion 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 

 account either of the forms or of the motions of these par- 

 ticles, and in some cases appears to have confounded them with 

 the elementary molecule, whose existence he was not aware of. 



Before I engaged in the inquiry in 1827, I was acquainted 

 only with the abstract given by M. Adolphe Brongniart him-? 

 self, of a very elaborate and valuable memoir, entitled " Re- 

 cherches sur le Generation et le Developpement de VEmbryon 

 dans les Vegetaux Phanerogames" which he had then read 



Z 2 before 



